roamer vs drifter

roamer and drifter both are nouns.

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

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

roamer: someone who leads a wandering unsettled life
drifter: a wanderer who has no established residence or visible means of support

Other hyponyms of roamer include nomad, clochard, floater, vagabond, vagrant.

roamer (noun)	drifter (noun)
someone who leads a wandering unsettled life	a wanderer who has no established residence or visible means of support