USB-C tells you the shape and hardware capabilities of the cable connector; USB 3 tells you the data transfer protocol and speeds of the cable.
CalDigit, USB-C, Thunderbolt 3
Thunderbolt 3 vs USB-C: What's the Difference?
USB-A vs. USB-B vs. USB-C: What Are the Differences?
Is USB 3.0 the same as USB C? Can you plug a USB C into a USB 3
What's the Difference Between Thunderbolt 3 and USB-C?
Thunderbolt™ vs. USB-C®: Similarities and Differences
What are the differences between USB-C and Thunderbolt 3?
Is USB 3.0 the same as USB C? Can you plug a USB C into a USB 3
Is USB 3.0 the same as USB C? Can you plug a USB C into a USB 3