Within a talent agency, there different types of agents who specialize in a particular type of client…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, a client will have agents from all divisions as a part of their team. For example a comedian may also write for TV and act in movies, therefore he would need the proper agents on his team representing him in each of those disciplines.