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USB4 vs USB-C: The Protocol And Connector Explained

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USB4 vs USB-C: The Protocol And Connector Explained

USB-C connects devices, but it's USB4 that defines their performance. Unlike standard USB-C cables, certified USB4 cables deliver lightning-fast speeds and superior power efficiency. To simplify consumer experience, confusing version numbers will be replaced with clear speed-based branding. For Indian consumers, investing in certified USB4 cables enhances device connectivity and ensures efficient charging, making it a smart choice.

Sahil Mohan Gupta

Published: Aug 17, 2026, 02:54PM IST

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USB4 vs USB-C: The Protocol And Connector Explained

USB-C describes the oval, reversible plug that fits into most modern laptops and phones. USB4 is the protocol governing how fast data moves, how much power flows, and whether video can pass through that same connector. Every USB4 device uses a USB-C port, yet most USB-C ports and cables lack USB4 speed support. The distinction matters because a $6 charging cable and a $40 certified USB4 cable share the identical connector shape but deliver different performance in every measurable way.

Key Highlights

About The Author

Sahil Mohan Gupta

At heart, I am a storyteller drawn to the watershed moments that bend the technology landscape. I braid narrative with data, humanise statistics, and trace the arc from first spark to world-changing impact. My reportage, features and reviews are witty, sardonic, visual and vivid, using anecdote to illuminate rather than eviscerate. As a technology journalist with over sixteen years of experience, I have travelled the world and the seven seas, covered every major tech conference worth its lanyard, chronicled the defining breakthroughs of the last decade and a half, and played a pivotal role in launching some of India’s most important technology publishing platforms across web, print and TV. In my current role as Editor of Gadgets Now Studios, I bring that experience, instinct and editorial firepower to the table, with the mandate of scaling the brand to towering heights. When I am off the clock, I am usually lost in music, from underground electronic and progressive rock to stone-cold blues. I am also an incurable F1 nut, a hangover from my previous life as an auto journalist, and always game for a jam session with friends, where I do my best to make my guitar gently weep.

USB-C is a reversible physical connector; USB4 is a data protocol that can run through it
USB4 offers speeds up to 40 Gbps, with Version 2.0 pushing 80 Gbps bidirectional and 120 Gbps asymmetric for displays
A standard USB-C cable may only support USB 2.0 at 480 Mbps, while a certified USB4 cable handles 40 Gbps data plus 240 W power delivery
The USB Implementers Forum replaced version-number branding in 2026 with speed-based marks: USB 80 Gbps and USB 40 Gbps
USB4 is backward compatible with USB 3.2, USB 2.0 and Thunderbolt 3, but requires certified cables to reach rated speeds
In India, certified USB4 cables range from around Rs 1,000 to Rs 2,949 depending on length, power rating and brand

What USB-C Actually Is

USB-C is a 24-pin connector specification defined by the USB Implementers Forum. The plug is reversible, which means it fits either way up, and it carries power, data and video signals through the same physical interface. The connector itself dictates nothing about performance. A USB-C port on a budget smartphone may support only USB 2.0 at 480 Mbps, while a USB-C port on a professional laptop may support USB4 at 40 Gbps or Thunderbolt 4 at 40 Gbps. The shape is identical; the capability is determined by the protocol the manufacturer has wired behind the port.

Power Delivery runs through USB-C as a separate specification that negotiates power levels between devices. The current USB PD 3.1 standard can deliver up to 240 W through a USB-C cable with the Extended Power Range profile, enough to charge gaming laptops and large monitors. A USB-C cable rated for 60 W carries a different internal construction from one rated for 240 W, yet both use the same connector. This is why cable markings and certification matter more than the plug shape itself.

What USB4 Actually Does

USB4 is a protocol standard released in 2019 and built on the Thunderbolt 3 protocol contributed by Intel. It defines how data, video and power share bandwidth across a USB-C connection. USB4 supports three main signaling tiers: 20 Gbps, 40 Gbps, and 80 Gbps bidirectional for Version 2.0. An asymmetric mode in USB4 Version 2.0 can push 120 Gbps in one direction for display-heavy workloads while maintaining 40 Gbps in the reverse direction.

The protocol allocates bandwidth between data and video tunnels on demand, which means a single USB4 port can handle an external GPU, a 4K monitor and file transfers at the same time with bandwidth allocated on demand instead of fixed reservation. The USB4 specification published by the USB Implementers Forum requires backward compatibility with USB 3.x and dedicated compatibility with USB 2.0, a requirement that ensures older devices and cables still function when plugged into newer ports.

It also supports Thunderbolt 3 alternate mode as an optional feature, though Thunderbolt 3 compatibility is required only for certain device types. The standard is defined for USB-C connectors alone, which means USB4 exists only on USB-C and never on USB-A or USB-B ports. This exclusivity is intentional: the USB Implementers Forum sought to reduce consumer confusion by converging on a single connector type for high-performance applications. Other connector formats such as USB-A and USB-B lack USB4 support, a deliberate choice to simplify the ecosystem for manufacturers and consumers alike.

Why USB-C Cables and USB4 Cables Are Not Interchangeable

A generic USB-C cable purchased from a retail bin almost always supports USB 2.0 internals, capping data transfer at 480 Mbps. That speed is adequate for charging a phone or syncing small files, but it will bottleneck an external SSD or a docking station. For USB4 performance, the cable must carry certified USB4 wiring with proper shielding and an E-Marker chip that tells the host and device what speeds and power levels the cable supports. Missing that chip, the connection falls back to the lowest common denominator.

How USB4 Version 2.0 Changes the Landscape

USB4 Version 2.0, announced in 2022 and reaching consumer devices in 2025 and 2026, shifts from NRZ to PAM-3 modulation. This change allows 80 Gbps bidirectional bandwidth over the same USB-C connector, with an asymmetric mode that pushes 120 Gbps in one direction for high-resolution display output. The specification maintains backward compatibility with USB4 Version 1.0, USB 3.x and USB 2.0, but the higher speeds require new cables and new host controllers.

In 2026, the USB Implementers Forum updated its certification and trademark rules to replace version-number branding with speed-based markings. Products now carry labels such as USB 80 Gbps or USB 40 Gbps rather than USB4 or SuperSpeed USB. This change aims to reduce the confusion that has plagued USB branding for years, where version numbers such as USB 3.2 Gen 2x2 meant little to average buyers. The new system makes the capability explicit: the number on the cable or port tells you the maximum speed in gigabits per second.

How Thunderbolt 4 and USB4 Relate to Each Other

Thunderbolt 4 is a certification program managed by Intel that sits on top of USB4. A Thunderbolt 4 device is a USB4 device that meets stricter minimum requirements: 40 Gbps bandwidth guaranteed, support for two 4K displays or one 8K display, 32 Gbps PCIe data transfer, and 15 W minimum power delivery for laptop charging. USB4 devices, by contrast, can ship with as little as 20 Gbps bandwidth, single-display support, and 7.5 W power delivery, depending on what the manufacturer chooses to implement. Intel charges licensing fees for Thunderbolt certification, which adds cost to devices and cables that carry the lightning bolt logo.

In practice, most premium laptops from Apple, Intel and AMD now ship with ports that support both USB4 and Thunderbolt 4, making the distinction less relevant for buyers of high-end hardware. The difference matters more in the mid-range and budget segments, where a USB4 port may lack the PCIe bandwidth needed for an external GPU or the display bandwidth for dual 4K monitors.

Thunderbolt 4 cables are branded with a lightning bolt logo and the number 4, while USB4 cables carry the USB logo with a speed rating such as 40 or 80. Both use the same USB-C connector, so the logo is the only visual clue at the point of purchase.

What Buyers in India Should Know

India's market for USB-C and USB4 accessories has expanded as laptop and smartphone manufacturers have converged on the USB-C connector. The challenge for Indian buyers is the same as elsewhere: the connector shape offers zero visual indication of capability. A Rs 300 USB-C cable from a local electronics market may charge a phone fine but will cripple a USB4 docking station or external monitor setup. Certified cables from brands such as Belkin, Ugreen and Anker are now available through Indian e-commerce channels, with prices starting around Rs 1,000 for basic 40 Gbps passive cables and climbing to Rs 2,500 or more for 240 W active cables with braided construction.

The Indian government's push for local electronics manufacturing under production-linked incentive schemes has yet to make a dent in USB4 cable pricing, as the active chips and high-grade copper conductors are still imported. Buyers should look for the USB-IF certification logo and explicit speed markings rather than relying on the USB-C shape alone. For most users, a single 40 Gbps USB4 cable rated for 100 W or 240 W can replace multiple specialised cables, provided the laptop, phone and charger all support USB PD at compatible wattages. This makes the upfront investment in a certified cable worthwhile for anyone planning to use docking stations, external monitors or fast-charging setups.

USB4 vs USB-C: The Core Difference SummarisedUSB-C is the road; USB4 is the speed limit and traffic rules. The connector provides the physical path, but the protocol determines what can travel along it and how fast. A USB-C port lacking USB4 support is like a single-lane road: functional for basic trips but inadequate for heavy loads. The cable you plug in determines whether you get a motorway or a dirt track.

A USB4 port on a USB-C connector is a multi-lane highway with dynamic lane allocation, capable of handling data, video and power at the same time at speeds that approach internal PCIe bus rates. The confusion between the two has cost consumers money and performance since USB-C first appeared, and the 2026 speed-based branding from the USB Implementers Forum is a long-overdue attempt to make the distinction visible at the point of purchase.

USB Standard Comparison Table

Specification	USB-C (Connector)	USB4 (Protocol)	USB4 Version 2.0
What it is	Physical connector shape	Data and video protocol	Updated protocol standard
Maximum speed	Varies by implementation	40 Gbps	80 Gbps bidirectional, 120 Gbps asymmetric
Power delivery	Up to 240 W (with PD 3.1)	Up to 240 W (with PD 3.1)	Up to 240 W (with PD 3.1)
Video output	Depends on Alt Mode support	Single display minimum, dual 4K typical	Enhanced display bandwidth
Backward compatibility	N/A (connector)	USB 3.x, USB 2.0, Thunderbolt 3	USB4 v1, USB 3.x, USB 2.0
Cable certification	Not required	USB-IF certified recommended	USB-IF certified required for 80 Gbps
Typical cable price (India)	Rs 300–800	Rs 1,000–2,949	Rs 1,500–2,949

USB-C Port Capability Comparison

Port Type	Data Speed	Power Delivery	Video Output	Typical Use Case
USB-C USB 2.0	480 Mbps	Up to 60 W	None	Budget phone charging
USB-C USB 3.2	5–20 Gbps	Up to 100 W	DisplayPort Alt Mode	Mid-range laptops
USB4 20 Gbps	20 Gbps	Up to 100 W	Single 4K	Entry-level ultrabooks
USB4 40 Gbps	40 Gbps	Up to 240 W	Dual 4K or single 8K	Professional laptops
USB4 80 Gbps	80 Gbps	Up to 240 W	Multiple 8K	Workstations, pro devices
Thunderbolt 4	40 Gbps	15 W min, 100 W max	Dual 4K or single 8K	Premium laptops, Macs

FAQs

Is USB4 the same as USB-C?

No. USB-C is a physical connector shape; USB4 is a data protocol that runs through USB-C ports and cables. All USB4 devices use USB-C connectors, but most USB-C devices and cables do not support USB4 speeds. A USB-C port on a budget phone may only handle USB 2.0 at 480 Mbps, while a USB4 port on a laptop can transfer data at 40 Gbps or higher.

Can I use any USB-C cable for USB4?

No. A standard USB-C cable typically supports USB 2.0 at 480 Mbps or USB 3.2 at up to 20 Gbps. To achieve USB4 speeds of 40 Gbps or 80 Gbps, you need a certified USB4 cable with proper shielding, thicker conductors and an E-Marker chip that communicates speed and power capabilities to the host and device.

What speed does USB4 Version 2.0 offer?

USB4 Version 2.0 supports 80 Gbps bidirectional bandwidth and an asymmetric mode that delivers 120 Gbps in one direction for display-heavy workloads while maintaining 40 Gbps in the reverse direction. It uses PAM-3 modulation instead of the NRZ signaling in USB4 Version 1.0.

How much power can USB-C and USB4 deliver?

Both USB-C and USB4 can support USB Power Delivery 3.1 with Extended Power Range, which delivers up to 240 W at 48 V and 5 A. However, the actual power depends on the cable rating, the charger and the device. A cable rated for 60 W cannot safely deliver 240 W even if the port and charger support it.

What is the difference between USB4 and Thunderbolt 4?

Thunderbolt 4 is a stricter certification built on top of USB4. It mandates 40 Gbps bandwidth, dual 4K display support, 32 Gbps PCIe data and 15 W minimum power delivery. USB4 allows manufacturers to ship with lower minimums: 20 Gbps bandwidth, single-display support and 7.5 W power. In practice, many premium devices support both standards.

How do I identify a certified USB4 cable?

Look for the USB-IF certification logo and speed-based markings introduced in 2026: USB 40 Gbps or USB 80 Gbps. Certified cables also list their power rating, such as 60 W, 100 W or 240 W. Avoid cables with vague labels like "USB-C fast charging" or "high speed" that lack specific speed and wattage figures.

end of article

P J

(2 days ago)

Well written .
A confusing subect is a bit easier to understand.