boy Friday vs helper

boy Friday and helper both are nouns.

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

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

boy Friday: a male 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 boy Friday include assistant, help, supporter, adult male, man.

boy Friday (noun)	helper (noun)
a male 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