helper vs bestower

helper and bestower both are nouns.

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

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

helper: a person who helps people or institutions (especially with financial help)
bestower: person who makes a gift of property

helper (noun)	bestower (noun)
a person who helps people or institutions (especially with financial help)	person who makes a gift of property
a person who contributes to the fulfillment of a need or furtherance of an effort or purpose