vapor bath vs bathing

vapor bath and bathing both are nouns.

Word	Noun	Adjective	Verb	Adverb
vapor bath	Yes	No	No	No
bathing	Yes	No	No	No

As nouns, bathing is a hypernym of vapor bath; that is, bathing is a word with a broader meaning than vapor bath:

vapor bath: you sweat in a steam room before getting a rubdown and cold shower
bathing: the act of washing yourself (or another person)

Other hypernyms of vapor bath include washup.

vapor bath (noun)	bathing (noun)
you sweat in a steam room before getting a rubdown and cold shower	immersing the body in water or sunshine
a room that can be filled with steam in which people bathe; `vapour bath' is a British term	the act of washing yourself (or another person)