wet blanket vs killjoy

wet blanket and killjoy both are nouns.

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

As nouns, wet blanket and killjoy are synonyms defined as:

Other synonyms of wet blanket include party pooper, spoilsport.

wet blanket (noun)	killjoy (noun)
someone who spoils the pleasure of others	someone who spoils the pleasure of others