working girl vs worker

working girl and worker both are nouns.

Word	Noun	Adjective	Verb	Adverb
working girl	Yes	No	No	No
worker	Yes	No	No	No

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

Other hypernyms of working girl include fille, girl, miss, missy, young lady, young woman.

working girl (noun)	worker (noun)
a young woman who is employed	sterile member of a colony of social insects that forages for food and cares for the larvae
a woman who engages in sexual intercourse for money	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