renter vs roomer

renter and roomer both are nouns.

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

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

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

Other hyponyms of renter include leaseholder, lessee, boarder, lodger.

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