married couple vs family

married couple and family both are nouns.

Word	Noun	Adjective	Verb	Adverb
married couple	Yes	No	No	No
family	Yes	No	No	No

As nouns, family is a hypernym of married couple; that is, family is a word with a broader meaning than married couple:

Other hypernyms of married couple include family unit.

married couple (noun)	family (noun)
two people who are married to each other	primary social group; parents and children
	people descended from a common ancestor
	a social unit living together
	(biology) a taxonomic group containing one or more genera
	a collection of things sharing a common attribute
	an association of people who share common beliefs or activities
	a loose affiliation of gangsters in charge of organized criminal activities
	a person having kinship with another or others