The difference in question is the "found" mechs have more armor to them. For instance I found my first Regis on the Reefs, got it up to my piloting level of 89 and it has 1,236 armor value attached to it. By way of comparison I bought a Regis, which I also brought up to my pilot level, equipped it exactly the same as my "found" Regis, and it has 1,190 armor value attached to it. Now that is only a 46 point variance in armor which does not sound like a lot truthfully, but during combat that 46 armor variance could be the determining factor between a win or a loss.
This is unlike the Ignis mecha which were found fully intact with their weapons, and I am unsure of the Aspis mecha as I only had one that was found when they first started popping up across the Galaxy. But as for the Regis itself there is a confirmed difference in the armor between what was found on the Reefs and what is mass produced by Star Factories at present. It seems that the found Regis mecha are made just slightly differently, packing more dense armor onto them and still being able to maintain the same stat values as what we have now being mass produced and sold.
Speculations abound as to why this mecha is built to contain slightly more armor, yet still retain the same base stats of a mass produced mecha. Some sources in the scientific community simply point out that they are original Forerunner designs and as such they are tougher through a means we have yet to discover in our current mech making capabilities. Others think they are simply made from a stronger form of Ferrite which we no longer have access to due to the resource itself being mined out long ago, or still hidden away on a world we have yet to find in our current gateway networks. Whichever the reason all that is known for certain is that the found mechas are tougher, more durable, and much nastier in combat than the mass produced versions from Star Factories.
Submitted by Pat Willis#224534