Registering a domain and hosting one is often mistaken by a lot of people to be one and the same thing. These are actually two separate services - the domain registration is the actual name and nothing else, while the hosted domains feature refers to the amount of already registered domain names that you can accommodate within the same hosting account and have website files and emails for them. Your sites will work in exactly the same way regardless of whether the domains are registered and hosted in one 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 web site if you don't host this domain name in some account so that records for it are created and it starts opening the data from that account.