Thunderbolt cables are slightly different, but are USB-C cables that support Thunderbolt alternate mode. Thunderbolt 3 uses a higher speed, 40Gb/s, that require

Thunderbolt cables are slightly different, but are USB-C cables that support Thunderbolt alternate mode. Thunderbolt 3 uses a higher speed, 40Gb/s, that require tighter tolerances and special cables. There are also Thunderbolt 3 cables that are out-of-spec for USB 3.1 Gen 2. I think can use Thunderbolt on USB3 cables at slower speed. USB4 unified them, making 40Gb/s standard speed and adding faster speeds. It is still confusing cause USB4 doesn't have to support Thunderbolt 3. Also, USB4 tunnels USB, Displayport, and PCI Express so there is no Thunderbolt alternate mode.