That really depends.
You can book whatever through
aaa.
You can not book a aaa discounted package through disney.
You can book a aaa discounted room through disney.
Usint aaa does not guarantee a discount. AAA discounts are limited and not available during holiday season.
Making it a package doesn not make it cheaper or more expensive exactly. A package is the combination of the rack rate cost of the components, and gives you some small extras like mini golf discounts (if you book a package through aaa there are more little extras). You have to have a package to get the
ddp. If you do not want the ddp you can save more money by booking a room only through either Disney or AAA and then purchasing your tickets separately - through aaa or undercovertourist.com or whatever.
Now as to if booking with Disney or AAA is cheaper....
If you want a package and the only discount you can get is aaa, then booking with aaa is cheaper since you can only book aaa discounted packages with aaa.
However, if there is a disney special on a package, you may find that a better deal than the aaa deal. You can not add the aaa discount to a disney discount. AAA can still book that for you but it would be the same price with Disney or AAA.
Since you can book a room only with a aaa discount either through aaa or Disney then the price for that reservation would be the same either way.