What’s the difference between probation & parole?

Probation is granted by the sentencing judge. Parole is early prison release granted by prison officials. Parole is similar to probation in that the offender is free from incarceration, with rights limited by the parole conditions. Conditions of parole tend to be similar to but more restrictive than probation conditions.

Parole has been abolished in some states. These states keep inmates until the end of their given term, then release them without supervision. This approach is in keeping with the theory that prison is to punish, not to reform; if that's the aim, there's no reason to continue supervision with a released inmate.