What are the differences between aicd and pacemaker?

AICD and pacer: An AICD almost always has a pacemaker as part of its circuitry. The ICD has a wire that monitors heart electrical function and circuitry to sense that electrical activity and respond with a cardioversion shock or a smaller pacemaker stimulus. The pacer doesn't have the cardioversion circuitry just the sense/pace circuitry. The ICD needs a bigger battery because it has to put out a larger discharge