squirt gun vs squirter

squirt gun and squirter both are nouns.

Word	Noun	Adjective	Verb	Adverb
squirt gun	Yes	No	No	No
squirter	Yes	No	No	No

As nouns, squirt gun and squirter are synonyms defined as:

squirt gun and squirter: plaything consisting of a toy pistol that squirts water

Other synonyms of squirt gun include water gun, water pistol.

squirt gun (noun)	squirter (noun)
plaything consisting of a toy pistol that squirts water	plaything consisting of a toy pistol that squirts water