For some reason the Windows 8 x64 Pro ISO that I got from TechNet and the Upgrade ISO is different. Is there any reason for the differences? One of the big ones is size. The downloaded ISO from the upgrade program is ~0.6GB smaller than the one I pulled from my TechNet account. TechNet ISO: A5889F86 Upgrade ISO: 6F8E5826 P.S. - Found the difference in size in the install.wim file. Why is it smaller?