American spelling vs water vapor

American spelling and water vapor both are nouns.

Word	Noun	Adjective	Verb	Adverb
American spelling	Yes	No	No	No
water vapor	Yes	No	No	No

American spelling (noun)	water vapor (noun)
English orthography used in the United States (characterized by 'analyze', 'center', 'usable')	water in a vaporous form diffused in the atmosphere but below boiling temperature