It is kind of like a clean motel vs a more upscale hotel. Both have various Disney extras, but that's the basic. Many deluxes are quite close to one or more parks and have some type of unique mode of transportation, like the monorail at some, the boat to MK at all the monorail resorts plus Wilderness Lodge (my favorite resort), the boats at some of the epcot deluxes. The theming is generally more elegant at the deluxe resorts, while it is very fun at the values.
I think it comes down to what you can afford. An idea is staying for one night at a deluxe maybe, just for fun, or 2 for the full feel. Do it at the end of your stay so you're not torn away from it if you love it maybe? I try to stay at the resort I want to and keep in mind budget constraints at that time, I don't want to be at a deluxe but have to worry about money while there.
My next trip is to Pop in may hopefully. With increased air and hotel costs, thats the one I selected. I decided last time the mods aren't worth it for what I want, but deluxes are. I can't justify the expenditure atm though for one.