As a reseller you have access to a number of different tools to help manage your account:
WebHost Manager
WebHost Manager, also known as "WHM" is the core of your reseller account, it is used to create and manage your hosting accounts. From within WHM you can manage every single aspect of your reseller account as well as your customers' web hosting accounts.
cPanel
cPanel is the end-user interface, you can use cPanel to manage your own reseller account and your users will also access cPanel to administer their own web sites.