Questions about the embedded GUI

I saw lvgl and it looks interesting in terms of the high quality GUI it provides, which made me wonder:

-What are the technical and programmatic differences between the embedded GUI and the GUI used in desktop applications such as gtk?

-Is an external library used to draw elements such as the cairo library, and event handling by a library such as the xlib library, or is it done in another way?

-Is the embedded gui suitable for building desktop applications on common computers such as laptops with Linux system such as ubuntu?