Having been "educated" early in my villa ownership between the difference of an attached spa (which we have) and a hot tub I have to put my two pennies worth in.

We have a spa attached to the pool and have been told from several knowledgeable sources that the spa is not designed to have more heat to it than the actual pool. The warm water system feeds both together (and therefore spa heat cannot be had without the pool heat on). In practice the spa does tend to be significantly warmer than the pool because you have the warm water directed at a smaller space. The spa bit I think refers more to the bubbles (which can be very refreshing on a hot summers evening...)

Now if there is a hot tub/ jacuzzi whether in ground or stand on deck type that is completely separate to the pool then it has it's own heat source and tends to be used at temperatures much higher than above mentioned spa.

Jackie