Within a talent agency, you typically have different types of agents…not all of them are referred to as “talent agents”.
Literary agents work with writers and directors. Motion picture lit agents represent writers/directors who work in feature film and TV lit agents represent writers/directors who work in…you guessed it…TV.
Talent agents represent with actors & actresses.
Book agents represent authors.
Public appearance agents represent comedians and public speakers
Commercial agents represent actors and actresses but are only concerned with booking them jobs in TV commercials and other forms of advertising.
Voice-over agents represent voice-over actors.
A lot of the time, client will have agents from all divisions as a part of their team. For example most TV writers also work in the feature film work and vice versa.