wet blanket vs colloquialism

wet blanket and colloquialism both are nouns.

Word	Noun	Adjective	Verb	Adverb
wet blanket	Yes	No	No	No
colloquialism	Yes	No	No	No

wet blanket (noun)	colloquialism (noun)
someone who spoils the pleasure of others	a colloquial expression; characteristic of spoken or written communication that seeks to imitate informal speech