The differences in the intended markets made the two products vastly different. The focus of engineering on the commercial line was all about production efficiency and beating the competition while protecting the bottom line. The government designs were driven by archaic military standards and bulletproof construction (literally), damn the cost.
What was frustrating for me as design manager was the complete lack of exploitable similarity between the two lines. Two different companies at two different locations may as well have built them. No production improvements discovered on the commercial line could be applied to the government units because of the constricting standards. And no aspect of the robust government design could be applied to the commercial units because of cost.