The most noticeable difference is the sensation. A whirlpool’s water jets come with the classic, high pressure, deep massaging jets that most people have come to associate with hydrotherapy. An air tub, on the other hand, is a more generalized, effervescent feeling.he most noticeable difference is the sensation. A whirlpool’s water jets come with the classic, high pressure, deep massaging jets that most people have come to associate with hydrotherapy. An air tub, on the other hand, is a more generalized, effervescent feeling.