Well, both jail and prison are areas where people are sent for confinement. Jail only holds people who are either awaiting trial, meaning there to answer charges, but have not yet been convicted or holds people who are sentenced to a crime and the confinement is less than a year. So if someone is going to serve a six month sentence, they don’t go to prison for that. They go to jail. If someone is in custody and can’t bond out until they answer their charges, they wait in jail.
Prison, first of all, is only for felonies. If you’re convicted of a felony, a person who’s been sentenced to confinement above a year will be sentenced to prison. Prison is only for people who have been sentenced. It’s not where they are sitting and waiting for trial. And prison is only for sentences longer than a year, that’s why a typical minimal prison sentence is one year and one day, because it’s greater than a year.