roomer vs renter

roomer and renter both are nouns.

Word	Noun	Adjective	Verb	Adverb
roomer	Yes	No	No	No
renter	Yes	No	No	No

As nouns, renter is a hypernym of roomer; that is, renter is a word with a broader meaning than roomer:

roomer: a tenant in someone's house
renter: someone who pays rent to use land or a building or a car that is owned by someone else

Other hypernyms of roomer include tenant.

roomer (noun)	renter (noun)
a tenant in someone's house	someone who pays rent to use land or a building or a car that is owned by someone else
	an owner of property who receives payment for its use by another person