The way it was explained to me is that the AAA discount is 10% for the deluxe resorts and 15% for the value and moderates. You can book room only reservations with the discount from either Disney or AAA, but if you want the MYW package with a AAA discount, you must book through AAA. (By the way, with the package, the discount only applies to the room, not the dining plan or park passes.)