semiautomatic pistol vs handgun

semiautomatic pistol and handgun both are nouns.

Word	Noun	Adjective	Verb	Adverb
semiautomatic pistol	Yes	No	No	No
handgun	Yes	No	No	No

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

semiautomatic pistol: a pistol that is a semiautomatic firearm capable of loading and firing continuously
handgun: a firearm that is held and fired with one hand

Other hypernyms of semiautomatic pistol include pistol, shooting iron, side arm, semiautomatic firearm.

semiautomatic pistol (noun)	handgun (noun)
a pistol that is a semiautomatic firearm capable of loading and firing continuously	a firearm that is held and fired with one hand