Hot tub or spa?
The terms spa and hot tub have been used synonymously in the business since the early years of the industry. Originally they meant two different things; spa was used to describe a therapeutic bath built out of acrylic or some other thermoplastic, while hot tub meant a circular bath, or tub, usually wood. Wooden hot tubs were popular as recently as the late 70s and early 80s, but were soon eclipsed by the rapid advances of portable acrylic spas. Still, the term hot tub stuck.