Linux was written from scratch, and is loosely based on Unix.
I like this description of the difference between them:
As such, there are similarities between Linux and OS X, but that's about it.Quote:
There is an old saying about BSD vs. Linux: “BSD is what you get when a bunch of UNIX hackers sit down to try to port a UNIX system to the PC. Linux is what you get when a bunch of PC hackers sit down and try to write a UNIX system for the PC.”