I really can't comment on the prices, but yes, both are made by Watkins. Hotsprings is thier flagship hot tub line, but I have no reason to believe Caldera is a less quality product. Chas, I belive sells both and should be able to comment if they are priced in the same range, and the nuiances between the two tubs.
The major diffences in these tubs appear to be
1)The Jetsetter offers the moto massag, a total of 14 jets driven by a 1.6 HP pump.
2) Caldera offers 27 jets, and a 2hp pump.
3) filtration. Caldera offers a 50 sf pleated filter, while the Jetsetter has 90 sf and "no by pass" filtration.
Wet test and take the one the fits you best. (Assuming there is no major swing in $$)