The difference between a state and federal prison is the government body that operates it. State prisons are operated by state governments, and federal prisons are operated by the federal government. Federal prisons are run by the Federal Bureau of Prisons (BOP) and generally have higher levels of security than state prisons.  The BOP may hold inmates over whom a different government maintains jurisdiction. To have custody of a prisoner, a state or the BOP must physically hold that person in one of its facilities. You can find where an inmate is housed using an Inmate Locator on this site.