I was advancing on an enemy archer on the far end of the battle field. I sent both a spearman unit amd a warge spearmen unit after the archer as far as they could go, and both ended in their turn standing right next to each other.
I would have expected the warg unit to be a few tiles ahead. (They both started their turns side by side)
I don't know if this is by design, but IMO, it should be changed.