Correct about the parked domains, though incorrect about the add-ons.The_Magistrate said:Parked domain is one that you buy. www.somedomain.com You buy it somewhere else, point that host's DNS to x10's nameservers and your domain works here at x10.
Addon domains are simply that... added-on. So your x10 account is, aguy.x10hosting.com. Well, with addon domains, you can create anotherguy.aguy.x10hosting.com, or agirl.aguy.x10hosting.com.... Get it? That way, you can point that addon domain to a subdirectory in your account and create a completely different site.