Registering a domain name and hosting one is usually mistaken by a lot of people to be one and the same thing. They're in fact 2 separate services - the domain registration is the actual name and nothing more, while the hosted domains feature shows the amount of already registered domains you can accommodate in the same web hosting account and have site files and emails for them. Your sites will work in exactly the same way no matter whether the domain names are registered and hosted at the same place or are registered with company A and pointed to company B. Simply registering a domain name without hosting it will give you ownership, but will not enable you to have a site unless you host this domain name in some account so that records for it are set up and it starts opening the content from that account.