talking head vs verbalizer

talking head and verbalizer both are nouns.

Word	Noun	Adjective	Verb	Adverb
talking head	Yes	No	No	No
verbalizer	Yes	No	No	No

As nouns, verbalizer is a hypernym of talking head; that is, verbalizer is a word with a broader meaning than talking head:

talking head: a talker on television who talks directly into the cameras and whose upper body is all that is shown on the screen
verbalizer: someone who expresses in language; someone who talks (especially someone who delivers a public speech or someone especially garrulous)

Other hypernyms of talking head include speaker, talker, utterer, verbaliser.

talking head (noun)	verbalizer (noun)
a talker on television who talks directly into the cameras and whose upper body is all that is shown on the screen	someone who expresses in language; someone who talks (especially someone who delivers a public speech or someone especially garrulous)