whisperer vs utterer

whisperer and utterer both are nouns.

Word	Noun	Adjective	Verb	Adverb
whisperer	Yes	No	No	No
utterer	Yes	No	No	No

As nouns, utterer is a hypernym of whisperer; that is, utterer is a word with a broader meaning than whisperer:

whisperer: one who speaks in a whisper
utterer: someone who expresses in language; someone who talks (especially someone who delivers a public speech or someone especially garrulous)

Other hypernyms of whisperer include speaker, talker, verbaliser, verbalizer.

whisperer (noun)	utterer (noun)
one who speaks in a whisper	someone who expresses in language; someone who talks (especially someone who delivers a public speech or someone especially garrulous)
	someone who circulates forged banknotes or counterfeit coins
	an organism that can utter vocal sounds