These terms are often mistakenly used interchangeably. The primary definition of the word spa is an establishment such as a destination or resort spa. However, hot tubs are often referred to as spas for some reason.  Jacuzzi is a registered brand name of multiple products, though it is often used incorrectly as a generic term referring to hot tubs. The term we feel is correct for our cedar coopered-design tubs with heating/sanitation systems is “hot tubs”. We use the term “Ofuro” to describe our Japanese-inspired soaking bathtubs.