vapor vs clouding up

vapor and clouding up both are nouns.

Word	Noun	Adjective	Verb	Adverb
vapor	Yes	No	No	No
clouding up	Yes	No	No	No

As nouns, clouding up is a hyponym of vapor; that is, clouding up is a word with a more specific, narrower meaning than vapor:

Other hyponyms of vapor include boiling, clouding, smoke, smoking.

vapor (noun)	clouding up (noun)
the process of becoming a vapor	the process whereby water particles become visible in the sky
a visible suspension in the air of particles of some substance