witnesser vs talker

witnesser and talker both are nouns.

Word	Noun	Adjective	Verb	Adverb
witnesser	Yes	No	No	No
talker	Yes	No	No	No

As nouns, talker is a hypernym of witnesser; that is, talker is a word with a broader meaning than witnesser:

witnesser: someone who sees an event and reports what happened
talker: someone who expresses in language; someone who talks (especially someone who delivers a public speech or someone especially garrulous)

Other hypernyms of witnesser include beholder, observer, perceiver, percipient, speaker, utterer, verbaliser, verbalizer.

witnesser (noun)	talker (noun)
someone who sees an event and reports what happened	someone who expresses in language; someone who talks (especially someone who delivers a public speech or someone especially garrulous)