tl;dr: There are 6, it's unfortunately very confusing to the end user.
While I don't own any USB-C device yet, it's good to know that there are 6 kinds of USB-C to USB-C cables:
Here they are, current as of the USB Type-C™ Specification 1.4 on June 2019:
- USB 2.0 rated at 3A
- USB 2.0 rated at 5A
- USB 3.2 Gen 1 (5gbps) rated at 3A
- USB 3.2 Gen 1 (5gbps) rated at 5A
- USB 3.2 Gen 2 (10gbps) rated at 3A
- USB 3.2 Gen 2 (10gpbs) rated at 5A
Read more in How many kinds of USB-C™ to USB-C™ cables are there?, an article by Benson Leung.