It is my understanding that the Arc Fault Circiut Breakers have a micro-processor in them that looks at or samples the hot wire current waveform and will trip the breaker if the waveforn shows signs or patterns of arc faulting,either series or parallel arcs.
Ground fault breakers look at the hot wire current and the neutral current makes a comparison and trips the breaker if they are not within 5ma of one another.
Chris
