gunstock vs pistol grip

gunstock and pistol grip both are nouns.

Word	Noun	Adjective	Verb	Adverb
gunstock	Yes	No	No	No
pistol grip	Yes	No	No	No

As nouns, pistol grip is a hyponym of gunstock; that is, pistol grip is a word with a more specific, narrower meaning than gunstock:

gunstock: the handle of a handgun or the butt end of a rifle or shotgun or part of the support of a machine gun or artillery gun
pistol grip: a handle (as of a gun or saw) shaped like the butt of a pistol

gunstock (noun)	pistol grip (noun)
the handle of a handgun or the butt end of a rifle or shotgun or part of the support of a machine gun or artillery gun	a handle (as of a gun or saw) shaped like the butt of a pistol