Registering a domain and hosting one is usually mistaken by a lot of people to be the same thing. They're in fact 2 separate services - the domain name registration is the actual name and nothing more, while the hosted domains feature refers to the amount of already registered domain addresses which you 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 regardless of whether 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 name without hosting it will grant you ownership, but will not enable you to have a site if you don't host this domain address in some account so that records for it are set up and it starts opening the data from that account.