@Sarah977
Yeah there are always exceptions Sarah, even 'lively' ones under the stars, or in front of cows like this lead listing photo from an Airbnb not far from here.
You would definitely call that a bath, and lets face it, you can adapt most things to suit situations
But the general consensus is, a bathtub is indoors and a hot tub is outdoors.
But as @Anonymous says gym's have indoor hot tubs.
But for @Tin18005 to classify his bath with water jets included in the main bedroom a 'hot tub' is stretching the definition.
Cheers........Rob