I believe the rooms are the same size but the BWI rooms usually have two beds and the BWV studio has a queen bed and a sofa that pulls out. Having the sofa can make the room seem larger when the bed is put away. THe BWV rooms also come with a small frig.
Actually, I think it is only slightly bigger (by about 10 sq. ft), but it feels a LOT bigger because the couch is folded up giving you a ton more floor space (until you pull the couch out, at which time, it feels tight)... the studio also has a microwave/kitchenette area, which is handy...