I agree with all the previous posts. I will add that there is just an overall feel that the deluxe resorts are more themed, more attention to detail, more high end finishes, towels, products, etc. The pools are more creative (Stormalong Bay is pretty much a water park in itself! and really, a volcano??) and tend to have a view of a lake/boardwalk. Someone suggested visiting a few. You can walk from the EP back entrance to YC/BC and BWI within a few minutes. They are gorgeous. I remember my stay at BWI, we had a first floor room and our glass doors opened up to a courtyard where it was a small walk to a hot tub.
That said, if you can afford it, go deluxe. If you don't spend any time at the resort because you are at the parks without breaks, are not "pool people" or tend not to eat at your resort or at TS, it may not be worth the cost.
The most noticeable differences from POR to deluxe are going to be size (deluxe are more easily walkable), interior hallways, and quicker transportation.