While they do share the same connector
USB-C port is fast,
T3 port is much faster,
On USB-C, you can connect external stuff such as hard drives, mobiles phones, SSD drives, Ethernet, as well as older USB stuff.
On T3 you can connect all of these, even all at the same time, plus external screens and external AVB units.
AVB, Audio/Video Bridging, moves medias in realtime on your network. On OSX It only works on REAL T3 Ethernet adapters, so steer clear off all the USB-C only cheap options.
If you want to connect external screens, external SSD storage and/or AVB stuff go for the genuine T3, because it is 4 times faster and AVB ready. Sonnet, Elgato or Caldigit make real T3 adapters and hubs worth the investment…
What do you really want to do with the T3 / USB-C ports on you machine ?