drifter vs bum

drifter and bum both are nouns.

Word	Noun	Adjective	Verb	Adverb
drifter	Yes	No	No	No
bum	Yes	Yes	Yes	No

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

drifter: a wanderer who has no established residence or visible means of support
bum: a vagrant

Other hyponyms of drifter include beachcomber, sundowner, hobo, tramp.

drifter (noun)	bum (noun)
a wanderer who has no established residence or visible means of support	the fleshy part of the human body that you sit on
	a vagrant
	a person who is deemed to be despicable or contemptible
	person who does no work

drifter (adjective)	bum (adjective)
	of very poor quality; flimsy

drifter (verb)	bum (verb)
	ask for and get free; be a parasite
	be lazy or idle