They are basically the same resort with different decor, but I jotted down some differences below:
> YC rooms all have a full balcony or patio - some BC rooms have a standing room only balcony.
> The "counter service" for both is located at the BC - BC Marketplace.
> BC is about a two minute closer walk to Epcot than YC. YC is closer by a minute to the boat dock.
> YC is a quieter resort mostly because BC has the character breakfast at Cape May Cafe which draws alot of families and subsequently alot of noise in the lobby area.
> YC decor is darker, richer colors - BC is lighter, airy, beachy theme.
> YC has the Yachtsman Steakhouse which is our favorite place to eat!
Both resorts share the pool and buses.
The walk to Epcot is about 7 minutes from YC - about 5 from BC - walk to DHS is about 20 minutes.
So, really, it's more a preference to the theming and maybe if you prefer a more quiet, relaxed type area and then, of course, the balcony.
I don't think you will go wrong with either!