If you are charged in federal court, the case is much more serious than if you were being prosecuted for the same crime in state court. One exception are Illegal entries, which can only be prosecuted by the US Attorney in federal court; without a criminal record, it may be possible to move your case quickly through a fast track to early deportation.
A conviction for most other types of federal cases, from drug offenses to internet sexual misconduct to violent crimes by Native Americans on Indian lands, result in a term of years with the US Bureau of Prisons. The federal marshals can remove someone from another state without formal extradition proceedings, and at the first summary hearing the magistrate judge explains the nature of the charges and the maximum potential penalties. The magistrate will schedule a second hearing, the arraignment, for the next morning. If you have not yet hired an attorney, a federal public defender or CJA attorney will be appointed to represent you. Even if you are represented by a public defender at these first hearings, it is still possible to hire a private lawyer at a later date as substitute counsel.