partner vs spousal equivalent

partner and spousal equivalent both are nouns.

Word	Noun	Adjective	Verb	Adverb
partner	Yes	No	Yes	No
spousal equivalent	Yes	No	No	No

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

partner: a person's partner in marriage
spousal equivalent: a person (not necessarily a spouse) with whom you cohabit and share a long-term sexual relationship

Other hypernyms of partner include domestic partner, significant other, spouse equivalent, relation, relative.

partner (noun)	spousal equivalent (noun)
an associate in an activity or endeavor or sphere of common interest	a person (not necessarily a spouse) with whom you cohabit and share a long-term sexual relationship
a person's partner in marriage
a person who is a member of a partnership

partner (verb)	spousal equivalent (verb)
provide with a partner
act as a partner