FBI and U.S. Marshalls?

Question

What's the difference between FBI and U.S. Marshalls?

Answer 1

Both are part of the Department of Justice, but perform different function:

The FBI is an investigative and domestic intelligence agency. Their priorities are to protect the United States from terrorist attack, foreign intelligence operations and espionage, and cyber-based attacks and high-technology crimes; combat public corruption at all levels, transnational/national criminal organizations and enterprises, major white-collar crime, and significant violent crime.

The US Marshals Service is the enforcement arm of the federal courts. They are responsible for apprehending wanted fugitives, providing protection for the federal judiciary, transporting federal prisoners, protecting endangered federal witnesses, and managing assets seized from criminal enterprises. They also also executes all lawful writs, processes, and orders issued under the authority of the United States.