Yes, the Grand Regina is different from Club Regina.
If you picture the hotel property as you enter from the highway, the hotel is in the center, Club Regina on the left, and the Grand Regina is on the right.
As I recall, Club Regina has been owned and operated by Raintree all along. The Grand Regina was being built by Raintree, but Starwood purchased the rights to the remainder of the unbuilt project.
To my knowledge, Starwood has never had a connection with Club Regina, other than sharing some of their properties with Westin-branded hotels.