Types
Initial hard drives for the Xbox 360 came in sizes as small as 20 GB, but Microsoft has released hard drives with storage capacities as large as 250 GB since the console's debut in 2005.
Identification
The size of hard drives cannot be ascertained by looking at the drive. Connect it to the console and go to "System Settings" on the Xbox 360 Dashboard to access files and determine the amount of gigabytes on the drive.
Features
Hard drives with more gigabytes allow players to store more files. In addition to game saves, players can store entire Xbox and Xbox Live Arcade games on their hard drives as well as movies and music files.