revolver vs pistol

revolver and pistol both are nouns.

Word	Noun	Adjective	Verb	Adverb
revolver	Yes	No	No	No
pistol	Yes	No	No	No

As nouns, pistol is a hypernym of revolver; that is, pistol is a word with a broader meaning than revolver:

revolver: a pistol with a revolving cylinder (usually having six chambers for bullets)
pistol: a firearm that is held and fired with one hand

Other hypernyms of revolver include handgun, shooting iron, side arm.

revolver (noun)	pistol (noun)
a pistol with a revolving cylinder (usually having six chambers for bullets)	a firearm that is held and fired with one hand
a door consisting of four orthogonal partitions that rotate about a central pivot; a door designed to equalize the air pressure in tall buildings