In the new dev diary, it was mentioned that the three bodytypes have different footstep noises. I can only assume that heavy footsteps are louder, because heavies clearly weigh 4 times as much as a light. Of course, the footsteps might just be deeper, but even that would e more noticeable.
I imagine a heavy in armour will sound like a rhino patroulling the area.
Whereas a light in cloth-tights will sound like a panther.