To my understanding, the piston differences are in the alloy used for the different thermal expansion values existing between the chrome bore and the iron sleeve bore. The aluminum chrome bore cylinder dissipates heat much more efficiently, requiring less different piston to wall clearance as a result. The iron bore piston would require more heat to get the skirt to proper tolerance. The rings should be dimensionally the same, but different composition. I believe the iron bore uses a chrome ring, which you wouldn't ever use on a chrome bore. I haven't looked at the compression distance, (wrist pin ht.), between the 100 & 200. Bear in mind that a portion of the part number probably refences model. Richard would know for sure, but my guess is the same part could be used in multiple models, and still have multiple numbers. I've seen it in done all over the motorsports industry.
KP