rec room vs playroom

rec room and playroom both are nouns.

Word	Noun	Adjective	Verb	Adverb
rec room	Yes	No	No	No
playroom	Yes	No	No	No

As nouns, playroom is a hyponym of rec room; that is, playroom is a word with a more specific, narrower meaning than rec room:

rec room: a room equipped for informal entertaining
playroom: a recreation room for noisy activities (parties or children's play etc)

Other hyponyms of rec room include canteen, family room, game room, rumpus room.

rec room (noun)	playroom (noun)
a room equipped for informal entertaining	a recreation room for noisy activities (parties or children's play etc)