Registering a domain name and hosting one is usually mistaken by a lot of people to be the same thing. They are in fact two different services - the domain registration is the actual name and nothing else, while the hosted domains feature reveals the amount of already registered domain addresses which you could accommodate within the same web hosting account and have website files and emails for them. Your sites will work in precisely the same way regardless 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 site until you host this domain in some account so that records for it are created and it starts opening the information from that account.