County jails and prisons have a handful of differences that range from function to environment, according to HG.org. Most notably, county jails serve short-term inmates, while prisons house those who have been sentenced to more significant crimes and spend longer periods of time behind bars.
As of 2015, there are about 3,600 county jails in the United States, explains Criminal Law Lawyer Source. A jail, which is operated by the county in which it is located, houses prisoners who have been recently accused of a crime and are awaiting sentence, or those who have been convicted of misdemeanors and are serving short sentences that typically won't exceed more than a year or two. Unlike a prison, jails lack notable social, work and rehabilitation programs, mostly focusing on a prisoner's day-to-day needs for the duration of their stay.
On the other hand, there are about 100 state and federal prisons across the country that incarcerate convicted felons serving longer sentences, notes Criminal Law Lawyer Source. Depending on whether a crime is of a state or federal nature, prisoners are sent to a large facility that's run by either the state in which it is located or by the Federal Bureau of prisons. State and federal prisons operate a variety of programs and options for their inmates, including minimum security options, halfway homes, work-release programs and educational opportunities, according to HG.org.