From the pictures above it looks like heads and weapon arms could be interchangeable. Horse tails too.
Notice that the guy in lower right has a different head and weapon than the guy riding the same horse in a different picture above. Also the horse has a different tail, and the horse up and to his left has the same tail as the horse in the picture above.
Additionally, the center rider has a different arm than the same rider at the top of the photos, and the heads are positioned differently.