The terms spa and hot tub are often used interchangeably when referring to a large tub of jetted hot water. However according to Wikipedia, these two words are actually quite different.
Spa (n); A spa is a location where mineral-rich spring water (and sometimes seawater) is used to give medicinal baths.
- A commercial establishment offering health and beauty treatment through such means as steam baths, exercise equipment, and massage.
Hot Tub (n); A hot tub is a large tub or small pool full of water used for hydrotherapy, relaxation or pleasure.
The most obvious difference between these two is their actual use and location. Whereas a hot tub can have spa like qualities, a spa is often a standalone establishment or in-ground structure that also provides health treatments. Conversely, a hot tub is portable and has its own plumbing and electrical control systems.
Even though they are not necessarily interchangeable, both spas and hot tubs offer a form of hydrotherapy and relaxation. The only thing it “bubbles” down to is use and location!