I guess the main differences are that the Dolphin has double beds, and the Swan has queen size beds.
The Swan also has a different bathroom set-up, they call it a "Hollywood Bath" meaning there are two sinks, one behind the door where the tub and toilet is, and one directly outside. Makes getting ready to go out easier. The bathroom at the Dolphin is set up more like the Disney moderates, meaning the tub and toilet are behind a door (no sink in with it) and the sink is right outside. BUT--across from that is a nice little area with a bench and mirror where you can put on make-up, etc.
I thought that our room at the Dolphin seemed a little bigger square footage wise, but I can't be certain, it just could've been an illusion.
It seemed liked the Dolphin was a little closer to the Grotto Pool too, but not by miles or anything!
The Swan is the smaller of the two resorts, so the corridors don't seem as long, and the walk from the elevator to your room doesn't seem as long.
Having stayed at both now, I can say we prefer the Dolphin! Tubbi's Buffeteria is there, as well as the Dolphin Fountain, the arcade and the laundry facilities. More festive lobby too!
As far as views go...you can get just as good (or bad) at either, depending on your location.
Either resort is a great choice, but I prefer the Dolphin.