In today's world, you might hear people referring to the Jacuzzi in their backyard as a hot tub or spa interchangeably. Today, both terms are used interchangeably, though they actually originally had different meanings, much like comforters and bedspreads. Jacuzzi is the trade name for all of these devices, just as Kleenex and Xerox are used to describe facial tissues and copiers, respectively. However, there are actually a few key differences between the two types of water tubs.
A hot tub is traditionally a wooden tub that holds more than one bather at a time. The water inside a hot tub is heated so that all bathers can enjoy a nice soak. Redwood and cedar are some of the most popular woods used to construct hot tubs. Unlike spas, hot tubs did not traditionally have jets in them, though many modern models do. Because the water is usually still, traditional-style hot tubs often develop a slippery film which can be hazardous if bathers are not careful getting in and out of the tub. Modern hot tubs & spas both have jets now, which have made hot tubs popular once again. Additionally, wooden hot tub manufacturers now use filters to help keep the water clean and free of gunk.