the major difference between the Python action and that of the Diamondback was size/proportion...that and the frame mounted firing pin of the Python vs the hammer mounted one of the Diamondback.
if you're looking at a picture of one without a size reference, the easiest way to tell is looking at the hammer spur. the Diamondback's is swept back at a lower angle
if you're looking at a picture of one without a size reference, the easiest way to tell is looking at the hammer spur. the Diamondback's is swept back at a lower angle