chief assistant vs helper

chief assistant and helper both are nouns.

Word	Noun	Adjective	Verb	Adverb
chief assistant	Yes	No	No	No
helper	Yes	No	No	No

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

chief assistant: the most helpful assistant
helper: a person who contributes to the fulfillment of a need or furtherance of an effort or purpose

Other hypernyms of chief assistant include assistant, help, supporter.

chief assistant (noun)	helper (noun)
the most helpful assistant	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