Basically there is only 1 major difference between the two. We have stayed at both of them many times. (We 1st only stayed at the YC because of the "balcony" issue. Balconies are available in 99% of all YC rooms whereas BC rooms a large portion only has a step out variety.) Then we moved to BC once when it was unavailble, fell in love and never went back. The major difference is not the balcony issue, not the location BC closer to epcot, not BC being blue and YC grey.

ITssssssss: its the attitute, "feel" of the resorts. They are nite and day different. YC very refined, quiet, elegant, sophistcated feel. BC is fun, relaxed, vacation--y, more family orientated.
Otherwise both resorts are great. Great pool (SAB)

Great location, good parking. Good Cm's.
Mky