The ocean villas are closer to the snorkel trail, which is at the main beach. The ocean villas are also closer to the restaurant, zip lines, and closer to more food trucks.
The lagoon villas are at the end of the developed beach, and you must either walk a bit (or hitch a ride on the golf cart) to get back to the main snorkel trail. I’m not sure if you can snorkel in the lagoon, but I don’t see why not. You probably won’t see as many fish as you would out near the reef though.