More school. Electrophysiologists are cardiologist who have gone further in training to do highly advanced work on treating cardiac arrhythmias. They are basically the electricians of the heart world. Most ep's, as they are called, do not go general cardiology work, but most general cardiologists do a fair degree of arrhythmia management via medications. We leave the pacemakers and icd's to the ep's.
Heart rhythm. An electrophysiologist is a cardiologist who has special training in heart rhythms & devices & ablations.
Arrhythmia speciali. An electrophysiologist is a cardiologist with an extra two years training in the management of arrhythmias. They are board certified in both cardiology and ep. Ep's have the capability of performing certain procedures a cardiologist does not such as ablations, implantation of defibrillators.