billiard parlour vs billiard room

billiard parlour and billiard room both are nouns.

Word	Noun	Adjective	Verb	Adverb
billiard parlour	Yes	No	No	No
billiard room	Yes	No	No	No

As nouns, billiard parlour and billiard room are synonyms defined as:

Other synonyms of billiard parlour include billiard hall, billiard parlor, billiard saloon.

billiard parlour (noun)	billiard room (noun)
a room in which billiards is played	a room in which billiards is played