When you receive a sentence for a criminal conviction, there is the possibility that you will become incarcerated. Where you spend your time behind bars depends on a few factors.
The National Institute of Justice explains you could either go to jail or prison. They are not the same. While each facility houses prisoners who have criminal convictions and provides them with work opportunities, activities and daily needs, they are quite different.
The biggest difference is that local governments run jails. Because of this, they often lack proper funding. They may be rundown or have facilities that are not up-to-date. They may also be unable to offer activities or work for inmates.
Prisons receive funding from the state. They have higher budgets and can offer more to inmates. They will usually also be much larger facilities because they house more people and have the funding to build a bigger facility.
Typically, the lack of funding in jails is overcome by the fact that people serving time in them are only there for less than a year. Some people may only be there for a night until they bond out or transfer somewhere else. The turnover is fairly high in jails.
Prisons house those with sentences over a year. They are more long-term and therefore, need to have more funding to provide rehabilitation or other services that prepare inmates for when they will get out. Prisons will house the more violent offenders and may have a death row or special area for those who are serving life sentences. It usually depends on the state and its laws.
There are also internal differences between prison and jail, such as how inmates treat each other, but these things may vary from facility to facility.