difference between Parole officer & Probation officer

It depends on whether the person is on parole (released early from jail/prison after a Parole Board hearing), or placed on probation by the courts instead of being given jail time. If one violates their parole they can be sent back to jail. If one violates their probation the court can send them to jail.

I thought parole was when you are waiting for your case to be heard and probation is what you get when you have been released early.

no, that's being out on bond or bail.

Don't know where you got that idea, Nick. If you are sentenced to prison, your case is heard by a parole board at set intervals while you're doing your time. The parole board can order your early release, keeping you on parole, however. That means you're a free man but you have to keep your nose clean and report to a parole officer on a regular basis until the full term of your sentences is complete. You might, however, be found guilty of a felony but spared prison. The judge gives you a term of probation instead. The circumstances of dealing with a probation officer are essentially the same as with a parole officer: keep your nose clean and report regularly. In either case you face completion of a prison sentence should you come short of the requirements set by the court.