[tialaramex]

There are a bunch of related but distinct technologies with names here. For example:

CTAP is a protocol for say a PC, or a Phone to talk to an authenticator, maybe over USB or maybe Bluetooth.

WebAuthn is a W3C standard for how a web site can negotiate (via Javascript) exactly what we're going to authenticate and then perform the authentication.

Imagine you connect an external CD drive to your laptop. The CD can turn Red Book CD audio into PCM data, maybe the drive plugs in with a USB-C cable, and the drive uses a SCSI-based Mass Storage variant USB protocol to talk to the laptop, which has an XHCI USB controller, so your operating system needn't know the fine details of this precise PCI USB controller chip. Again, distinct technologies with their own names.