In order to make a website, you need 2 things - a domain and a web hosting plan for it. The domain registration is the actual website address which you type in a browser to reach a website, while the hosting space is where your site files will be. These are 2 very closely related, but individual services, even though many people assume that registering the domain name is enough. Just like the disk space and the monthly traffic features which a given website hosting plan features, there are a certain number of registered domain names that you can include as hosted i.e. you can have the web content for them in some account even when the domains are in fact registered through a different company. In technical terms, it doesn't matter whether a domain is registered and hosted with the exact same company or is registered with one company and directed to a different one - in either case your websites will function in exactly the same way.