Some of the major differences...
Distance to parks- Deluxe resorts will be close to at least a park (CR, Poly, GF, WL- MK; BC, YC, BWI- Epcot, DHS; AKL-AK)
Transportation- Deluxe resorts (except for AKL) offer a transportation alternative (boat, monorail, walk) besides bus to at least a park
Hallways-Deluxe have interior hallways while Value and Moderates have exterior hallways except for the suites at AoA (think about this carefully, with exterior walkways, it means your room's window is directly on the walkway whereas with interior walkways you have a window on the opposite side of the room and potentially a balcony or patio)
Restaurants- Mods and Deluxe have table service and quick service restaurants available, while Values have quick service only
Room Service- Can get room service at Deluxe resorts
Bar/Lounge- Mods and Deluxe have, Values don't (other than pool bars)
Amenities- I've found the towels to be better at the Deluxes vs. the Mods and Values
Themeing- Values have over the top, cartoonish themeing that tends to appeal to young children, Mods and Deluxes have more nuanced themeing
Bed Size- Values have doubles, Mods have queens (POR, POFQ, CSR) or doubles (CBR), Deluxes have queens
Room Size- Generally speaking, Values smaller than Mods smaller than Deluxes, but even within a category room sizes can vary (for example, with Deluxes, AKL and WL rooms are smaller than CR, Poly and GF rooms)
Pools- Available at all resorts, but Mods and Deluxes have a slide, while the Values don't
Hot Tubs- Available at Mods and Deluxes (other than Poly)
Fitness Centers- Available at Deluxes only (exception is that there is one at CSR which is a Mod)