girl Friday vs helper

girl Friday and helper both are nouns.

Word	Noun	Adjective	Verb	Adverb
girl Friday	Yes	No	No	No
helper	Yes	No	No	No

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

girl Friday: a female assistant who has a range of duties
helper: a person who contributes to the fulfillment of a need or furtherance of an effort or purpose

Other hypernyms of girl Friday include assistant, help, supporter, adult female, woman.

girl Friday (noun)	helper (noun)
a female assistant who has a range of duties	a person who helps people or institutions (especially with financial help)
	a person who contributes to the fulfillment of a need or furtherance of an effort or purpose