There are many different types of agents for different types of talent. The main types are theatrical (Television and Film) and commercial (for commercials). There are also dance, print, voice-over,etc. Your agent may represent you for one or more of these categories.
A talent manager is the personal guide for an individual model or talent. While management regulations vary from state to state, managers are among the sources that are intended to be packaging and training resources by such states as Florida.
Most casting directors operate in Los Angeles or New York, but there are still casting directors in other states as well. Casting directors are hired to cast talent for movies, shows, original features, commercials, TV programs, print work, fashion shows, runway, etc.