cPanel & WebHost Manager (WHM) is a next generation web hosting control panel system. Both cPanel & WHM are extremely feature rich as well as include an easy to use web based interface (GUI). WHM allows you to but is not limited to administering individual accounts, reseller accounts & performing basic system & control panel maintenance via a secure interface. For a complete list of features including screen shots of WHM, please click here.
cPanel is designed for the end users of your system and allows them to control everything from adding / removing email accounts to administering MySQL databases.