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?
Yes we would still prefer Linux. Windows is just a single object without any modularity. With Linux by itself is of course just a barebones kernal waiting to be added to. You can choose which gnu libraries to use you can chose which package manager to use you can chose which desktop environment to use (or ommit it entirely.) Windows doesn’t have that option.
As well since the source code for linux has been open for over 30 years people know how it works, it would take ages for people to study windows and actually figure out how to do anything with it.