What’s the difference between a Jacuzzi and a Hot Tub?
You say potato, we say root vegetable.... Is there actually any difference between a Jacuzzi and a Hot Tub?

In short: No, there is no real difference. A Jacuzzi is a hot tub.
In the same way that a Hoover is a vacuum cleaner, a Kleenex is a tissue or a Jet Ski is a personal motorized watercraft. These are brands that have come to be so well-known that the brand name becomes just as used the actual name of the thing it is a brand of. Sometimes, even more so to the point where people believe that is the thing’s name (for example, more people than not think the names Velcro and Heroin are actual words rather than trademarks.Yes, Heroin – trademarked by Bayer)
Is a Dyson vacuum cleaner a hoover? Yes – in terms of the way the word hoover has become an eponym for vacuum cleaners. But a Dyson is not a Hoover vacuum cleaner. See the difference?
Jacuzzi was the first brand of what we now refer to as Hot Tubs, all the way back in the mid-20th century when the company debuted its first whirlpool bath (called the Roman Bath) which was based on the patented a full body hydrotherapy pump that Candido Jacuzzi had developed to help treat his son’s arthritis. Between being the first company to be known for producing such products, along with endorsements and publicity from celebrities of the time (such as Jayne Mansfield), the name Jacuzzi soon became better known that the term whirlpool bath or hot tub. And over half a century later, the name Jacuzzi is still being used to denote any hot tub even if it’s made by someone else.