Obviuosly the server ISO is larger, and is larger the the storage space occupied by the installed system. It's because all the server components that even if not installed, are there. But still the base server (no server roles installed) is way lighter than any W10. It's counter intuitive until you understand how the windows installations are working since Vista
I think it possibly depends on your processor. Microsoft support WDDM 2.0 in both Skylake and Broadwell.
@antonio - Disable Scan with Windows Defender in context menu. Credit to the original poster moglai a few posts above, I had just looked up and posted the English translation. If memory serves me correctly there had been several suggestions on how to disable it - none of which stuck. The one by moglai did work and I assume still does?