The retention straps have been moved out to the sides to allow room for the water bottle pouch.
Webbing loops have been added to the anchors of these straps, for ice axe lashing points.
At the base of the Bergen an additional ice axe loop has also been added so you can now carry 2.
Other examples of moddifications ,
Some extra molle attached to the issue Bergen
Removable waist belt padding slips on over existing belt