Whoa whoa whoa... Biiiiiig difference here. A hot tub is where your uncle shows you his coffee-breath and gives you a back rub. He'll try to dissuade you from using corks or condoms, but will insist you meet his "stinky chicken". In a Jacuzzi; pretty much the same idea, but it's all consensual. The main difference is the part where it looks like someone dumped a barrel of mouths into a giant tub of buttholes.