I don't recall how much it's spelled out on the website, but something else to keep in mind.
Staying onsite includes the "Unlimited Express" which can be used as many times as you want during the day while it's valid.
the traditional purchased express pass is only good one time per attraction.... so no re-riding the Hulk back-to-back-to-back with the purchased express.
There is also the ability to purchase an Unlimted Express, but it's almost $100 per person per day above your theme park admission, so it can sometimes be more cost effective if you stay onsite for a single night.