Also take me as pedantic but I'd maybe a difference between:
- Wayland: protocol
- libwayland: helper library, you can choose to not use it for your own stuff (but others will likely depend on it)
- whatever compositor/display-server you're thinking about (Apache isn't HTTP)
- user applications (Google Chrome isn't HTTP either)

(And yes the wayland ecosystem has a lot of udev+linux-isms, basically because the folks that do not want udev/linux-isms didn't care about wayland for 10+ years, I was part of those btw)