First there was what is now known as the XBOX Original (http://en.wikipedia.org/wiki/Xbox). This is the first generation of the Microsoft Gaming Consoles.
Then in 2005 Microsoft released their second generation of the console called XBOX 360 (http://en.wikipedia.org/wiki/Xbox_360).
The main differences in these consoles is hardware. The XBOX360 contains improved hardware allowing for improved graphics, wireless controllers and headsets and extended media capabilities. The XBOX360 currently is available in two editions; Archade and Elite.
XBOX360 Arcade comes in a white case with no Hard drive, one controller and AV/Component cables.
XBOX360 Elite is black, comes with a 120GB Hard Drive, one controller and AV/Component cables.
The Hard drive is used to store saved games, music, videos and also users can install their games to improve load times and use less disc spin.
Complaints regarding the consoles is that the XBOX360 is considerably nosier than the original and also the XBOX360 is susptable to the "Red Ring of Death" (http://bit.ly/8tboh3)