I would think that the basic design principles would be the same with the emphasis on military stuff being from the point of view of survivability and the expected hazards of being under fire etc, whilst the civvy stuff will be more from a commercial point of view with regards to operating costs, maintenance intervals and the old bottom line of the $$.
The main issue for civvy machines would be from the legal point of view with liability and certification issues topping the agenda to keep the manufacturer out of court in the event of a catastrophe/incident that could in any way be laid at their feet.
That's my take on it, but I am sure there are more qualified folks out there who could better answer this.