I found the footwork to be a much greater change than the arm positions, but you're right, they do similar things very differently.

So, what's the reasoning behind the changes? Do the two styles teach different approaches to address attacks? Or, to use your example here, is the first move supposed to be able to lead to different kinds of options? Or, is it simply a question of addressing philosophical concerns?

My question put another way: if someone were a black belt in both forms, what would be her reason for choosing one of those stances over the other?