Bridge II - Different HW-Revisions

I have two Revisions of the Bridge II. One is Rev. B2 the other one is Rev. B5. The difference I could spot is that the older B2 has the USB host connector assembled.

As far as I remember this was meant for connection of a WiFi adapter, which was never realized?! Is there any other advantage in having the USB. Any more differences between B2 and B5?