hoarder vs scavenger

hoarder and scavenger both are nouns.

Word	Noun	Adjective	Verb	Adverb
hoarder	Yes	No	No	No
scavenger	Yes	No	No	No

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

Other hyponyms of hoarder include magpie, pack rat, miser, churl, niggard, scrooge, skinflint, penny pincher.

hoarder (noun)	scavenger (noun)
a person who accumulates things and hides them away for future use	any animal that feeds on refuse and other decaying organic matter
	someone who collects things that have been discarded by others
	a chemical agent that is added to a chemical mixture to counteract the effects of impurities