What are the area(s) of difference between Linux distributions that involve an actual incompatibility, or are there none?
It seems like most of the "differences" are essentially choices of application. For example, one distribution has one window manager and a different one has another. However, I can always just change the window manager. A more specific example is that Debian uses apt to get packages, but Arch use pacman. Can't I just install apt on Arch or pacman on Debian? Is there any fundamental difference that prevents me from doing this?