gleaner vs gatherer

gleaner and gatherer both are nouns.

Word	Noun	Adjective	Verb	Adverb
gleaner	Yes	No	No	No
gatherer	Yes	No	No	No

As nouns, gatherer is a hypernym of gleaner; that is, gatherer is a word with a broader meaning than gleaner:

gleaner: someone who gathers something in small pieces (e.g. information) slowly and carefully
gatherer: a person who is employed to collect payments (as for rent or taxes)

Other hypernyms of gleaner include accumulator, collector.

gleaner (noun)	gatherer (noun)
someone who picks up grain left in the field by the harvesters	a person who is employed to collect payments (as for rent or taxes)
someone who gathers something in small pieces (e.g. information) slowly and carefully	a person who gathers