common-law marriage vs marriage

common-law marriage and marriage both are nouns.

Word	Noun	Adjective	Verb	Adverb
common-law marriage	Yes	No	No	No
marriage	Yes	No	No	No

As nouns, marriage is a hypernym of common-law marriage; that is, marriage is a word with a broader meaning than common-law marriage:

common-law marriage: a marriage relationship created by agreement and cohabitation rather than by ceremony
marriage: the state of being a married couple voluntarily joined for life (or until divorce)

Other hypernyms of common-law marriage include matrimony, spousal relationship, union, wedlock.

common-law marriage (noun)	marriage (noun)
a marriage relationship created by agreement and cohabitation rather than by ceremony	the act of marrying; the nuptial ceremony
	two people who are married to each other
	the state of being a married couple voluntarily joined for life (or until divorce)
	a close and intimate union