revolver vs handgun

revolver and handgun both are nouns.

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

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

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

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

revolver (noun)	handgun (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