Bug fixes, DirectX 12 support and more. http://www.bit-tech.net/news/hardware/2015/07/30/amd-intel-nvidia-graphics-drivers/1
I don't get it, are they only releasing these drivers on their own web sites for the tech savvy people? If someone installs these isn't Microsoft just going to re-install what it considers the correct drivers via its forced updates.
In nVidias case it shouldn't provided the version number is higher than the driver on WU [based on my experiences manually install the drivers in the previews] And the problem with GFE [or at least its what happened to me] was it thought there was no driver installed after it installed the WU driver, and tried to install the driver from the site, however a restart and everything was fine.