Is it just / ?
I kid. But really, besides “its all a file”, if you take away the gui, is the only difference the syntax ? How libraries interact? How disks are mounted ?
If we stripped all ms’s junk out and made windows open source, would we still prefer linux?
When you get to a very basic level, is one of them more efficiently coded?
Haiku comes to mind
Haiku is pretty unix-like, I wouldn’t count it
Fun wiki hole there. Nice.