DEFINITIONS
Whirlpool - Whirlpool tubs typically have a 1.5 - 3 horse power pump with a few jets placed around the tub to provide powerful streams of water.

Airtub - An airtub usually has a pump with less power but has many timy jets around the tub. This gives a massage-like bath.

Both in One - A combination tub allows for the best of both worlds, usually allowing the decision of using the whirlpool jets, air tub jets or all of the jets at the same time.

Soaker - A soaker is simply the tub without any jets.