User blog comment:JediSpectre117/Regarding the surviving Prothean./@comment-2127131-20120218211056/@comment-4820017-20120219083248

What if the Protheans were similar to the Forerunners as in they had mutations for different classes of the species. The statues on Illos represented the high class, the thinkers. This Prothean that we have seen from concept art could be part of the warrior class, thats why there is a different look