WebHost Manager, or WHM, provides administrative control of your dedicated or Virtual Private Server (VPS). You use WebHost Manager to create individual accounts, add domains to your server, manage hosting features, and performing basic system and control panel maintenance.
cPanel is designed for managing particular domains or hosting accounts on your server. End users can control everything from adding/removing email accounts to administering MySQL databases.
For more information about cPanel and WebHost Manager, visit the cPanel website at http://www.cpanel.net.