roncoinc
Official Stihl Disser
The 120 series saw would be a good choice for your needs and usually can be had for a lower price than the other top brands of saws in the same class. The one difference that I know between the 120 and 120Si is in the carbs, the 120 uses a choke plate type carb setup and the Si uses a injector type carb setup where the lever on the carb is just rotated or flipped as some say it. The 120 super and the Si are both 68 cc engines and the older 120 was a 61 cc saw. The 120 super also has a fuel primer bulb on the left rear of the saw . There are most likely many other small details in differences between them and others may be able to fill in with some more info.
Pioneerguy600
The SI Ignition parts are different also. not cheap and hard to come by.
all the "si" and "I" saws seem to have the same ignition.. and i NEED that coil for one of mine,so i know..