unpaid worker vs worker

unpaid worker and worker both are nouns.

Word	Noun	Adjective	Verb	Adverb
unpaid worker	Yes	No	No	No
worker	Yes	No	No	No

As nouns, worker is a hypernym of unpaid worker; that is, worker is a word with a broader meaning than unpaid worker:

unpaid worker (noun)	worker (noun)
a person who performs voluntary work	sterile member of a colony of social insects that forages for food and cares for the larvae
	a person who works at a specific occupation
	a member of the working class (not necessarily employed)
	a person who acts and gets things done