Emcee and Talking head

Emcee noun - A person who acts as host at formal occasions (makes an introductory speech and introduces other speakers).

Talking head and emcee are semantically related. In some cases you can use "Talking head" instead a noun "Emcee".

Talking head noun - A talker on television who talks directly into the cameras and whose upper body is all that is shown on the screen.

Emcee and talking head are semantically related. Sometimes you can use "Emcee" instead a noun phrase "Talking head".