Unlike a coupon, a product discount area would allow you to specify that an item is on sale, such as a 50% off rack, and have that information come into a new sale automatically. This system is envisioned to work by first creating a discount group that specifies a dollar or percentage off discount. SKUs would then be added to the discount group and their price would be affected accordingly at checkout time.
Coupons will also include the option of applying to or not applying to items that are in a discount group.