Registering a domain and hosting one is usually mistaken by a lot of people to be the same thing. They are in fact 2 separate services - the domain address registration is the actual name and nothing more, while the hosted domains feature refers to the number of already registered domain names that one could accommodate in the same hosting account and have site files and email messages for them. Your sites will function in exactly the same way no matter if the domains are registered and hosted at the same place or are registered with company A and pointed to company B. Simply registering a domain without hosting it will grant you ownership, but will not allow you to have a web site until you host this domain address in some account so that records for it are created and it starts opening the content from that account.