Welcome to Mac Forums Sharpe!!
I don't want to sound like an unthinking Mac zealot, but there is huge depth in that "only" word in your "is the only difference...". The Mac OS X operating system, the software that comes with it, and the world of Mac software out there, plus the performance, stability and capability of all of that is HUGE!
It is rather like asking if the only difference between a Yugo and a BMW is where they are made. Both are cars, both have four wheels, an engine, seats, etc. At a very abstract level you could argue that both have the same basic hardware bits and bobs. BUT, there is a world of difference in the end user experience. Ditto for a Mac vs. a PC.
This does sound like zealotry, but it isn't. It is born out by hard facts. Mac OS X really is better than Windows in thousands of ways.