bigamy vs spousal relationship

bigamy and spousal relationship both are nouns.

Word	Noun	Adjective	Verb	Adverb
bigamy	Yes	No	No	No
spousal relationship	Yes	No	No	No

As nouns, spousal relationship is a hypernym of bigamy; that is, spousal relationship is a word with a broader meaning than bigamy:

bigamy: the state of having two spouses at the same time
spousal relationship: the state of being a married couple voluntarily joined for life (or until divorce)

Other hypernyms of bigamy include marriage, matrimony, union, wedlock.

bigamy (noun)	spousal relationship (noun)
the offense of marrying someone while you have a living spouse from whom no valid divorce has occurred	the state of being a married couple voluntarily joined for life (or until divorce)
the state of having two spouses at the same time