Not a trans girl but Wayland and x11 are display server protocols. A display server is the program that draws windows and stuff on the screen (plus some other things related to desktop environments), and these protocols are how the applications controllo their windows. X11 is very old and based on obsolete ideas. It is a less efficient protocol than Wayland, and has many security issues. The most prominent one is that any unprivileged program can read the entire screen and record any input. X11 development has for a long time revolved around a single display server that everyone used, called x.org, this is partly why it developed so fast. However the codebase is a mess because it started so long ago and developed so fast, so it’s almost untouchable. That’s why modern features like hdr and real multi display support will never arrive. Wayland is the modern protocol that will replace x11. It is built from the ground up to avoid the mistakes made by x11. Because of this, development is often stuck discussing esoteric scenarios, to make sure everything is perfect before adding it to the protocol. Unlike x11 there is not a single Wayland server, and this is why you will see differences between implementations. Unlike x11, Wayland is designed around modern computers. Unless you are using something that specifically only works on x11, you should use Wayland.