Shared Hosting has the ability to have add-on domains along with parked domains. An add on domain offers the ability to run multiple sites off of one shared hosting plan, while a parked domain simply forwards another domain to your main website. Shared hosting, however, is usually intended for one or two websites per account. Lack of control over multiple domains is what limits these types of accounts.
Reseller Hosting, however, is very flexible and is ideal for more than one website, or rather, domain. It allows you to neatly organize accounts, each having their own username, password, domain name, contact info, and preferences. As the name suggests, you are able to resell our resources (at any price), and make a profit for yourself. Reseller accounts include a special control panel, WHM (Web Host Manager), which is used to create, manage, and terminate other accounts.