dancing partner vs cooperator

dancing partner and cooperator both are nouns.

Word	Noun	Adjective	Verb	Adverb
dancing partner	Yes	No	No	No
cooperator	Yes	No	No	No

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

dancing partner: one of a pair of people who dance together
cooperator: an associate in an activity or endeavor or sphere of common interest

Other hypernyms of dancing partner include collaborator, pardner, partner, dancer, social dancer.

dancing partner (noun)	cooperator (noun)
one of a pair of people who dance together	an associate in an activity or endeavor or sphere of common interest