Im trying to find out the difference. It seems that an ignition coil converts the cars battery voltage from 12V to several thousand volts; whereas, a magneto creates several thousand volts without any input from the aircrafts battery.
You pretty much got it. A magneto creates its voltage by passing a magnet driven by the crankshaft of the engine past a coil. Every time the magnet passes the coil it induces a sharp current in the coil. A lot of small engines, like on lawn mowers, have magnetos.
I have built CD ignition circuits, and have one now. Basically what it does is use a high (audible) frequency DC-DC converter to generate a 300-400 volt charge on a capacitor, which is discharged through a standard ignition coil when electronically triggered. At low RPM, the current drain is very low, and increases as the RPM increases. At very high RPM it may exceed the current drain of a breaker point (old fashioned) automotive ignition system, depending on the choice of coil. The breaker point ignition circuit current drain depends only on the dwell time (the percentage of time the points are closed) and not on the engine RPM, so the current drain is independent of RPM. Commercially available replacement CD ignition circuits (e.g., Mark Ten Model B which I have) were designed to use the OEM breaker points as a trigger for the CD discharge.Cd ignitions are the hot setup ( capacity discharge)
they generate multiple sparks be engine revolution at idle that help to burn gasoline/air mixture more thoroughly
at hi rpm the CD has a real long spark time , up to 10 crankshaft degrees that helps burn the mix better
these CD ignitions are real voltage hogs and can run down a good battery a lot quicker than the old breaker point ignitions]