airgun vs paintball gun

airgun and paintball gun both are nouns.

Word	Noun	Adjective	Verb	Adverb
airgun	Yes	No	No	No
paintball gun	Yes	No	No	No

As nouns, paintball gun is a hyponym of airgun; that is, paintball gun is a word with a more specific, narrower meaning than airgun:

airgun: a gun that propels a projectile by compressed air
paintball gun: an air gun used in the game of paintball; designed to simulate a semiautomatic

Other hyponyms of airgun include BB gun.

airgun (noun)	paintball gun (noun)
a gun that propels a projectile by compressed air	an air gun used in the game of paintball; designed to simulate a semiautomatic