It's understandable if you've used "parole" and "probation" interchangeably -- they both describe the legal status of an offender who has been conditionally released into the world.
But parole and probation are not the same thing. They actually describe two different punishments and processes -- one carried out by the traditional criminal justice system, and the other by the correctional system.
Plus, only parole, by definition, involves jail.
This is because probation is actually an alternative to jail. Though a judge may order a defendant to serve probation in addition to prison time, it's often served alone.
On the other hand, parole is a conditional release from prison. A defendant is ordinarily sentenced to jail "with the possibility of parole." After serving a designated percentage of his sentence, he can ask the parole board to grant him early release. If he meets the requirements -- good behavior, usually -- he is paroled.
Unlike with probation, there is no judge involved.
Despite these differences, parole and probation do share one major similarity. Both probationers and parolees are subject to a list of conditions. They must meet with a supervising officer; attend counseling and rehab; hold a job; and/or not break the law. If they fail to comply with the rules of parole or probation, they can be sent to jail.
Still, in the end, it is a judge that revokes probation, and a parole board that revokes parole. Both parole and probation may ultimately have the same effect, but they do operate in slightly different spheres.