same-sex marriage vs couple

same-sex marriage and couple both are nouns.

Word	Noun	Adjective	Verb	Adverb
same-sex marriage	Yes	No	No	No
couple	Yes	No	Yes	No

As nouns, couple is a hypernym of same-sex marriage; that is, couple is a word with a broader meaning than same-sex marriage:

Other hypernyms of same-sex marriage include duet, duo, twosome.

same-sex marriage (noun)	couple (noun)
two people of the same sex who live together as a family	a pair who associate with one another
	a pair of people who live together
	(physics) something joined by two equal and opposite forces that act along parallel lines
	two items of the same kind
	a small indefinite number

same-sex marriage (verb)	couple (verb)
	engage in sexual intercourse
	link together
	bring two objects, ideas, or people together
	form a pair or pairs