water pistol vs squirt gun

water pistol and squirt gun both are nouns.

Word	Noun	Adjective	Verb	Adverb
water pistol	Yes	No	No	No
squirt gun	Yes	No	No	No

As nouns, water pistol and squirt gun are synonyms defined as:

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

Other synonyms of water pistol include squirter, water gun.

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