civil union vs marital status

civil union and marital status both are nouns.

Word	Noun	Adjective	Verb	Adverb
civil union	Yes	No	No	No
marital status	Yes	No	No	No

As nouns, marital status is a hypernym of civil union; that is, marital status is a word with a broader meaning than civil union:

civil union: a voluntary union for life (or until divorce) of adult parties of the same sex
marital status: the condition of being married or unmarried

civil union (noun)	marital status (noun)
a voluntary union for life (or until divorce) of adult parties of the same sex	the condition of being married or unmarried