If you want the dining plan, you have to book a package. The package also comes with some coupons, like for the arcade or mini-golf.
If you don't care about the dining plan, you can still book a package or a room-only (RO). Here are the differences:
1) Deposit: Packages require a $200 deposit. RO is one night's stay, which can be more or less than $200.
2) Pay in full: Packages must be paid in full no later than 45 days of arrival. RO may be paid in full on check-in.
3) Cancellation: Packages may be cancelled for a full refund before the 45 day mark, or there is a graduated penalty. RO may be cancelled for a full refund up to 5 days before arrival; after that, you lose the deposit.
4) Tickets: Unless you have an AP or are a DVC member, you must buy at least a one-day base ticket for a package (2 days if it's
free dining). For RO, you don't have to buy tickets at all through Disney; you can get them through an authorized reseller like Undercover Tourist for a small discount.