- Thunderbolt 3 is a superset of USB 3.1

- USB4 is built on Thunderbolt 3's protocol, implementing a subset of its mandatory features

- Thunderbolt 4 is a strict profile of USB4 (all optional features made mandatory)

- USB4 v2 introduced 80 Gbps signaling

- Thunderbolt 5 is a strict profile of USB4 v2 (again, optional features made mandatory)