roomer vs boarder

roomer and boarder both are nouns.

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

As nouns, roomer and boarder are synonyms defined as:

Other synonyms of roomer include lodger.

roomer (noun)	boarder (noun)
a tenant in someone's house	a tenant in someone's house
	a pupil who lives at school during term time
	someone who forces their way aboard ship