Just my opinion, but I found them to be very different and I mean different in a good way. To me, the GF feels like a secluded resort. It's quiet and there just doesn't seem to be much going on there. I find it very relaxing and I do like the way the buildings are set up around the resort. In comparison, we stayed at the YC this past December. Definitely more of a hotel feel, with all the rooms being located in one building. Huge, huge plus is that you are within minutes of the International Gateway in Epcot and all of a 10 minute boat ride to MGM. It seemed much more lively, especially with all the Boardwalk options right across the lake. One drawback was the view situation. At the GF, even the garden view is beautiful. At the YC, you could easily be looking at a roof top, or parking lot.
Tammi