Although the terms “jail” and “prison” are sometimes used interchangeably, most members of law enforcement distinguish between the two. Primarily, the difference is that a jail is used by local jurisdictions such as counties and cities to confine people for short periods of time. A prison, or penitentiary, is administered by the state, and is used to house convicted criminals for periods of much longer duration. Both are part of a larger penal system which includes other aspects of criminal justice such as courts, law enforcement, and crime labs.

Because a jail is designed for short time periods only, it tends to have less amenities than a prison. Individuals who are being housed in a jail have access to bathrooms and are provided with food and water, and in a low security jail, they may be able to socialize in common areas during certain periods of the day. Most jails are designed to hold a very small number of criminals, and have relatively lax security when compared to prisons, although in areas prone to violence, a jail may be run along very strict lines. A jail houses people who have been convicted to serve a short sentence, individuals awaiting trial, people who have not yet paid bail, and detainees who have just been picked up on suspicion of committing a crime. The criminals are processed through a booking procedure, and the criminal justice system decides what to do with them after that.

In a prison, the amenities are much more extensive, as some prisoners may be serving their lives behind bars. Prisons have exercise areas, common areas for eating and socializing in lower security areas, church facilities, and an educational facility which includes classrooms, libraries, and labs to work and study in. In lower security prisons such as those used to imprison people convicted of white collar crimes, the prison could sometimes be mistaken for a hotel. In most cases, prison inmates are expected to share cells with other inmates, and because of the long duration of most prison sentences, a complex social and political structure arises among the prisoners.

A prison is capable of handling far more prisoners than a jail is, and the prisoners are typically segregated on the basis of the types of crimes that they have been convicted of, as a safety precaution. In addition, in countries which still have capital punishment, a prison maintains facilities to carry out capital sentences, along with housing for criminals sentenced to this type of punishment. In general, the prison facility as a whole is very tightly secured, even if not all the criminals inside are violent, to prevent escapes or potential violence between wings of the prison. Prison staff are specially trained to work in a prison environment, and a board of governors appointed by the state oversees prison management.