figures differences between picture rulesbook and miniature

By rugal, in Runebound

It's not the first time I saw that (i also see this with drakon V3)

when taking a close look to the rulesbook picture of the heroes, we see steelhorns and Lyssa. They are red instead of grey, but it's not the real problem. Lyssa is almost the same as its mini.
but for Steelhorns, there's some differences : its legs are more wide open, its posture looks more aggressive and its look like a bit further feral. Nothing to looks like with the steelhorns mni we have. So my question here is simple : why the miniatures have been changed ? Someone knows ?