The big difference is the location. The GHVS are located in the GreatHouse Building on the 2nd and 3rd floors, so all of the rooms open into a hallway. The GVS are located in one of four smaller buildings, and all of them open to the outside. I'd be happy to send you a map if that would help (amy.welch@Hotmail.com).
We were just there on our honeymoon! July 27th-August 1st. I think if you are looking for a more private feeling out of he two, you should go for the Garden Verandah Suite. But if you want something closer to more people, the pool and restaurants stay in the Great House! We stayed in the GVS and loved it! You had the feeling of being alone, but also just a little walk away from the beach and restaurants!
Matt and I liked it so much we are planning our second trip to CSA for December of next year, can't wait! Good luck!!