The USB Dispute: USB4 vs Thunderbolt 3

USB-C brought the death of previous different USB connections along with its advanced features. The industry was able to move towards this new standardized connection type for future generations. USB 4 shares many of the same aspects of Thunderbolt 3, but how do they really compare?

Comparing The Two:

Similarities	Differences
40Gbps Transfer Speed Up to 100W USB PD USB-C Port	​USB4 is Backwards Compatible with Thunderbolt 3 USB4 can come in different modes (1 Lane 10Gbps to 2 Lane 40Gbps)

It's critical to know the difference and which is which when using devices that may or may not support both cable types. While both of them use the standard USB-C connector, Thunderbolt 3 has a small lightning bolt icon next to them. As for USB4, the ports have a speed rating next to the USB logo and should have a 40 on it (representing 40Gbps transfer speed).

What About Thunderbolt 4?

USB4 and Thunderbolt 4 are essentially identical in functionality. The features of Thunderbolt 3 aren't upgraded, instead the supported devices for Thunderbolt 4 are guaranteed to support at least 32Gbps in PCI Express bandwidth to the port. Devices supporting Thunderbolt 4 are able to output 4k on external displays or a single 8k display.

The guaranteed 32Gbps is what makes Thunderbolt 4 stand out, mandating a higher minimum standard while USB4 devices can support traditional USB 3.1 connection of 10Gbps or USB 3.2 20Gbps.

USB4 and Thunderbolt 4 cables will be almost identical and backwards compatible. Thunderbolt 3 will still be able to work with Thunderbolt 4 and USB4 connections, while older USB-C 3.2 connections won't be able to support the fast 40Gbps transfer speeds of USB4.

Thunderbolt 4 will support 100W Power Delivery just like USB4, meaning both cables will be able to charge any device that supports USB4 at full Power Delivery.