Q. My question is pretty simple - What is the difference between UNIX and MAC OS X?
A Mac OS X is an operating system with a graphical user interface, developed by Apple computer for Macintosh computers, based on UNIX.
Darwin is a free and open source, Unix-like operating system first released by Apple Inc. in 2000. It is a standalone operating system as well as the core set of components upon which Mac OS X was developed. It is primarily developed by Apple to support Mac OS X.
There are few differences:
a) File system – Mac OS X prefer to use HFS+ file system with slightly modified directory location.
b) X11 vs Aqua - Most UNIX system use X11 for graphics. Mac OS X uses Aqua for grpahics.