XOrg and Wayland are two different programs that serve the same purpose, which is to act as a sort of middleman between the graphics driver, the window manager(s), and the many programs you’re running.
XOrg is ancient. Early 80s ancient. It’s been added to since those days as need arose, and is therefore full of weird messy legacy stuff and jury-rigs. But it is also what Linux has used for a very, very long time, and is therefore like. Ol’ Reliable workhorse, yanno?
Wayland is a new and bold step that rewrites the entire system from the ground up to address the shortcomings of XOrg (don’t ask me to specify, I actually don’t know), it has, however, been criticised for not having (and devs downright not wanting it to have) certain features that XOrg has. But it can also run applications that expect XOrg with a thing (jargon escapes me) called XWayland.
Personally I’ve used both. And… Uh…
Wayland was a bit faster and smoother maybe? But it also caused some specific applications to misbehave and get all crashy-buggy. But that was a personal experience and may well have been my fault.