A cable with a USB-C plug at one or both ends often reveals little about what it’s capable of doing. Despite guidelines for labeling set by the USB-IF (the USB trade group) and Intel’s Thunderbolt division, you can wind up with multiple USB and Thunderbolt cables and adapters without a great idea of what they do.
USB 2.0 and 3.0’s Type-A connector and Thunderbolt 1 and 2’s Mini DisplayPort-like plug offered fewer options. The biggest difference was between USB 2.0 and 3.0—but you could quickly tell if your hard drive was constrained to the 480 Mbps speed of USB 2 or operating under the higher 5 Gbps overhead of 3.0.
But with USB-C and Thunderbolt 3 (and now Thunderbolt/USB 4), it’s more confusing since they use the same connector. Just look at the following illustration about USB-C options created by Intel to inspire positive feelings about Thunderbolt and tell me that it fills you with information rather than dread.
Read more at Macworld.com