The differences between supraventricular arrhythmias and ventricular arrhythmias are: 1. Different sites of occurrence: supraventricular arrhythmias occur mainly in the atria, sinoatrial node, and atrioventricular junctional zone. Ventricular arrhythmias occur mainly in the ventricles; 2. Effects on cardiac function: Common supraventricular arrhythmias, such as atrial premature beats, do not have much effect on cardiac function. Ventricular arrhythmias, commonly known as premature ventricular beats, cause ejection changes in the ventricles, and frequent or consecutive premature ventricular beats cause a decrease in cardiac function.