Thunderbolt/ USB 4 vs Thunderbolt 4

Thunderbolt 3 has 16 Gbps of bandwidth and Thunderbolt 4 has 32 Gbps of bandwidth.

see > https://www.owc.com/blog/whats-the-difference-between-thunderbolt-3-and-thunderbolt-4

and > https://www.intel.com/content/www/us/en/architecture-and-technology/thunderbolt/thunderbolt-3-vs-4.html

One thing required for a computer to get Thunderbolt 4 certification is for it to offer the ability to drive two displays over USB-C (DisplayPort) or Thunderbolt.

If you study Apple's Technical Specifications, you will find that

• Every Apple Silicon Mac that can drive at least two such displays, without turning off any built-in one, has either Thunderbolt 4 or Thunderbolt 5.
• Every Apple Silicon Mac that can drive only one such display – or that forces you to shut off a built-in display to use a second USB-C or Thunderbolt Display – has Thunderbolt 3.

You will also find that every Apple Silicon Mac has USB4 ports, and that no Intel-based Mac does. The first Apple Silicon Macs were either the first machines, or among the first, to implement the then-new USB4 standard.

What about them?

USB-C, Thunderbolt 3, Thunderbolt 4, USB 4 all use the same connector and are backwards compatible.

The only real difference, is the total number of bands (paths) that are offered.

Note that the Macs with the M4 Pro chip have Thunderbolt 5 ports with 80 Gbps for bidirectional transfer and up to 120 Gbps with Bandwidth Boost, which is double that of Thunderbolt 4.