People are often confused about the differences between probation and parole. Not only do they both start with the letter "p," but they both represent ways for people convicted of crimes to live out in society while under some form of supervision. What's more, they're both conditioned on good behavior—if the offender messes up, they're often sent to jail or prison. But probation and parole occur at different stages of the criminal justice process.
Probation is a period of court-ordered supervision in the community. A judge orders probation at sentencing. Probation can include jail time, but it's often an alternative to jail or prison. People who are granted probation must follow the terms and conditions ordered by the judge, such as obeying all laws, reporting to a probation officer, and submitting to drug testing.
Parole is granted by a parole board after an individual has served some—perhaps a lot of—prison time. The parole board grants parole based on proof of a prison inmate's good behavior, among other factors. If parole is granted, the parolee is released under supervision with terms and conditions, such as maintaining employment and not leaving the area without permission from a parole officer.