sidesman vs helper

sidesman and helper both are nouns.

Word	Noun	Adjective	Verb	Adverb
sidesman	Yes	No	No	No
helper	Yes	No	No	No

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

sidesman: (Church of England) an assistant to the churchwarden; collects offerings of money in the church
helper: a person who contributes to the fulfillment of a need or furtherance of an effort or purpose

Other hypernyms of sidesman include assistant, help, supporter.

sidesman (noun)	helper (noun)
(Church of England) an assistant to the churchwarden; collects offerings of money in the church	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