helper vs sparer

helper and sparer both are nouns.

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

As nouns, sparer is a hyponym of helper; that is, sparer is a word with a more specific, narrower meaning than helper:

helper: a person who helps people or institutions (especially with financial help)
sparer: someone who refrains from injuring or destroying

helper (noun)	sparer (noun)
a person who helps people or institutions (especially with financial help)	someone who refrains from injuring or destroying
a person who contributes to the fulfillment of a need or furtherance of an effort or purpose