It really hard to compare them fairly since they're quite different in scope; X11 wouldn't exactly be considered a Linux API. Win32 is also split between severa

It really hard to compare them fairly since they're quite different in scope; X11 wouldn't exactly be considered a Linux API. Win32 is also split between several modules and the functions don't quite correspond to the syscalls; it's basically a bunch of wrappers around the actual NT API, win32k and some userspace servers. So it's really hard to draw a line somewhere if you wanted to compare them.