frat house vs fraternity house

frat house and fraternity house both are nouns.

Word	Noun	Adjective	Verb	Adverb
frat house	Yes	No	No	No
fraternity house	Yes	No	No	No

As nouns, frat house and fraternity house are synonyms defined as:

frat house and fraternity house: a house used as a residence by a chapter of a fraternity

Other synonyms of frat house include chapterhouse.

frat house (noun)	fraternity house (noun)
a house used as a residence by a chapter of a fraternity	a house used as a residence by a chapter of a fraternity