Sweetwater had the Bahia where Sundance had the Optima. They are the same manufacturer but a different series. The name "Sweetwater" has been replaced by "700 series" I believe.
Sweetwater had few color choices where the Sundance had more. Electronics on the Sweetwater was lower end than on Sundance. I believe the Sundance tubs had stainless steel rings around the jets. Sweetwater had fewer jets.
This is based on what I remember from 2004 when I was shopping for my tub. If you can get a serialnumber, call the factory and ask them. Friends of mine have the Bahia and love it.