What is the difference between a criminologist and a CSI?

A criminologist is a person who specializes in learning about and understanding criminal behavior. They may study a crime scene but their intent is to determine the underlying actions of the criminal rather than obtaining physical evidence.

A crime scene investigator is a person who investigates crimes by visiting the crime scene and obtaining physical evidence.

It is possible for a person to be both a crime scene investigator (able to obtain physical evidence) and a criminologist (able understand the behavior and motivations of the criminal)

How can I intern as a CSI?
What do I have to do to become an FBI profiler?