There are 3 categories.

Value, the rooms are the smallest and they have double beds, but I know a lot of ppl who have stayed in these and love them. IMO, they are the best, "kid themed" resorts. They don't have table service, only quick service and the rooms are exterior corridors, like a motel. The pools don't have a slide. They just got fridges in POP, so that is an added plus. They only have one sink. They do not have covered (shaded) bus waiting areas, like the mod and deluxes do.

Moderates get you a slightly bigger room. All, except for Caribbean have queen sized beds. They are also exterior corridors, but include a dorm sized fridge and coffee maker, as well as a double sinks and a curtain or sliding doors that you can close to separate the sink/bathroom area from the room. All except French Quarter have table service (but Riverside is only a short walk away, they are sister resorts), all have counter service. The pools are a little nicer, with some quiet pools (except FQ, it is the smallest resort, so doesn't need a quiet pool), and a slide. I think that ppl said the towels are also supposed to be nicer. I would equate the Moderates to more of a Hampton Inn or Holiday Inn Quality. We stayed at POFQ and loved it, very quaint and small, I think it's actually a very romantic looking resort.

Deluxe, there Wilderness Lodge and Animal Kingdom are the deluxes that are slightly smaller (room size) than the other deluxes. The rooms are bigger, you get a fridge, coffee maker, some have an extra daybed for a fifth person, a patio and these are interior hallways. They have table and quick service options and these are the resorts that usually have some sort of themed or character meal. It is more upscale. Some offer a boat ride as transportation and some are on the monorail. The Epcot resorts offer you the ability to walk to Epcot and DHS parks.

There is also DVC, and while it is a timeshare, non-dVc owners can rent points. I won't get into it, but if you are interested, I am sure someone here can explain it better than I can, but basically you can usually rent points for $10-$13/pt and the rooms are a little bit nicer.

Personally, I originally was booked for Wilderness Lodge, b/c my DH was put off by the outdoor corridors, but when free dining came out, I switched us to POFQ (we both love New Orleans) and the exterior corridors were great, we saved $ and I don't regret it, I thought it was really nice, better than I would have expected for a moderate. There was actually a lot less noise IMO than interior corridors with the exterior corridors, b/c every time I stay at a regular hotel, I always hear a lot of noise in interior hallways. We automatically ruled out values, since we knew we wanted queen sized beds.