A Description of the different PC and Macintosh Operating System

Although computer families such as IBM PC-compatible and Macintosh can be distinguished on the basis of CPU type, it is mainly their choice of operating systems which gives them their particular identity. Microsoft dominates the market , with over 90% of all computer systems using one of the Windows operating systems - Windows XP, Windows Vista, and Windows 7. Even some systems using Microsoft's original Ms-DOS can still be found.

On the other hand, Macintosh computers use Apple's Macintosh Operating system (MAC OS).
To appreciate the differences between Windows and Mac OS, while Apple did not invent the graphical user interface, they were first to make a fully realized, commercially viable product. Microsoft produced their own graphical user interface - Windows.

Reference : http://books.google.com.au