gay woman vs woman

gay woman and woman both are nouns.

Word	Noun	Adjective	Verb	Adverb
gay woman	Yes	No	No	No
woman	Yes	No	No	No

As nouns, woman is a hypernym of gay woman; that is, woman is a word with a broader meaning than gay woman:

Other hypernyms of gay woman include gay, homo, homophile, homosexual, adult female.

gay woman (noun)	woman (noun)
a female homosexual	women as a class
	an adult female person (as opposed to a man)
	a female person who plays a significant role (wife or mistress or girlfriend) in the life of a particular man