marriage vs matrimony

marriage and matrimony both are nouns.

Word	Noun	Adjective	Verb	Adverb
marriage	Yes	No	No	No
matrimony	Yes	No	No	No

As nouns, marriage and matrimony are synonyms defined as:

marriage and matrimony: the state of being a married couple voluntarily joined for life (or until divorce)

Other synonyms of marriage include spousal relationship, union, wedlock.

marriage (noun)	matrimony (noun)
the act of marrying; the nuptial ceremony	the ceremony or sacrament of marriage
two people who are married to each other	the state of being a married couple voluntarily joined for life (or until divorce)
the state of being a married couple voluntarily joined for life (or until divorce)
a close and intimate union