A lot also has to do with theming.
At the Beach Club, the color scheme is pink, sea foam green and white, and your ambiance is more seaside elegance. I believe it is said to have been modeled on Newport RI.
At Yacht Club, you're looking at hardwood floors, navy blues, solid reds, golds, and a more Martha's Vineyard, ship-like setting. I find it more formal.
The Readers Digest version I tell people is, as follows...
Beach Club- Louder, more kid-filled, more laid back, think seashells, seahorses and sand.
Yacht Club- Quieter, seems more adult friendly, more formal, think nautical, anchors, and sailors knots.
Hope that helps!