OK, then, in total: All Eldar (so far) bigger butts, wider hips, slimmer boots. Maybe slimmer gauntlets. Scorpions, Dragons, Dark Reapers, Warp Spiders and Shining Spears (if/when they show up) Autarchs need a beefier version of the base armor with thicker plates. Scorpions in particular need taller shoulder pads, it looks like. In fact, if you keep the current boots and gloves, give them taller shoulder pads and beefed out chest, thighs, upper arms, widen the hips a bit, and of course bigger butts, I think that will do Scorpions. Most of the differences between the heavier aspect warriors comes down to shoulders and backpacks. And helmets, of course.
There's also a cosmetic 'heavy aspect armour' (probably a different name) item you can buy in the rogue trader store, for the classes with the heavier armour, so bear that in mind.
Agree with most comments so far, I gotta say the Scorpions look like a teenage version not solid looking enough even the Avengers seem starved to death.
Don't forget this is the basic lowest ranked looks. More armor and a better filled out armor look might be coming as you rank up.
Well. more ornate armour as you progress is standard for wargames online, but isn't it Orks that get bigger as they get more powerful?
...is that a euphemism? Anyway, to the Scorpions... I agree, they need to be chunkier. That's blatantly the same base model reskinned. Similarly for Dark Reapers and Fire Dragons. It looks like the mesh section of the armour is identical, then the plates have been added on. The base model needs to be beefier and then the plates added. Though if that's very awkward, then I'm willing to accept it how it is. It does look okay, so I wouldn't have called it a massive priority.
Looking at your profile picture right now and that Scorpion is actually pretty damn slender and non meaty in the arms. They said there will be bulkier and more fancy looking armors to unlock for customization. This is probably supposed to be like a rookie youngin' Scorpion.