What is difference between cardioversion and defibrillation?

Voltage: Cardioversion means using a stimulus to change the heart's beat from an abnormal rhythm to a normal one. Certain drugs can be used, or electricity, usually only a low voltage is required unless the abnormal rhythm is a very dangerous one called ventricular fibrillation. When the rhythm is ventricular fibrillation, usually more voltage (electricity) is needed, and it is called defibrillation.