What is the difference between municipal and federal agencies?

In the United States, law enforcement agencies function as part of their respective governments. Local law enforcement agencies are usually police departments and sheriff's offices that serve a city or county. Local law enforcement agencies may have a wide range of duties, but usually involve uniformed patrol, investigation of crime, and sometimes also running a local jail facility and serving process on behalf of local courts. State agencies, such as state police, highway patrols, and state investigative agencies, work state-wide and tend to have responsibility for investigating crimes that have a larger geographic scope (large auto theft rings and narcotics trafficking are two examples), or that require more resources than most local agencies have available (in some states, the state police units supply specialized resources such as SWAT teams, helicopters, or major case investigators to smaller agencies on an as-needed basis). Depending on the locale, state police or highway patrol/troopers may be responsible for primary response to calls for service in isolated or rural areas. Federal law enforcement agencies typically specialize in certain types of criminal investigation, and rarely have a role responding to crimes in progress. The FBI is probably the most well known agency, and takes a lead role investigating organized crime, terrorism, public corruption and violations of other Federal Laws. They also provide a lot of support services to agencies across the nation, and participate in multi-agency task forces. Other agencies, such as the DEA, specialize very closely (in the case of the DEA, they enforce mainly federal drug laws). Other examples of specialized federal agencies include the Postal Inspection Service, the US Marshals Service, and the BATFE (Bureau of Alcohol, Tobacco, Firearms and Explosives), also known as the ATF. The Secret Service is another well known agency, which has the dual role of protecting the President and other government officials, as well as investigating serious financial crimes and currency counterfeiting. There are a multitude of federal law enforcement agencies, many of which do not receive much press. How each agency works depends upon the extent of its size, mission and jurisdiction. While historically law enforcement officers from different agencies worked separately and did very little information sharing and coordination, today it is a very different story. It is not uncommon to see local police officers working side by side of officers from nearby police departments, as well as with teams comprised of various types of state and federal agents. What one agency lacks in knowledge, manpower or financial or tactical resources, other agencies are able to fill in the gap, maximizing the ability of such teams to leverage their skills and assets toward accomplishing the law enforcement mission. As agencies modernize and attempt to do more with less, it is common for them to share information and work together to get more work done with fewer officers and at a lower cost than going it alone.