kidnapper vs capturer

kidnapper and capturer both are nouns.

Word	Noun	Adjective	Verb	Adverb
kidnapper	Yes	No	No	No
capturer	Yes	No	No	No

As nouns, capturer is a hypernym of kidnapper; that is, capturer is a word with a broader meaning than kidnapper:

kidnapper: someone who unlawfully seizes and detains a victim (usually for ransom)
capturer: a person who captures and holds people or animals

Other hypernyms of kidnapper include captor, criminal, crook, felon, malefactor, outlaw.

kidnapper (noun)	capturer (noun)
someone who unlawfully seizes and detains a victim (usually for ransom)	a person who captures and holds people or animals