A fair amount has been changed or added, I'd say. I recommend the Windows Internals book if you're interested in learning about the Windows kernel. The 7th edition just came out.
The impression I formed back in the late-2000s and early 2010s when I was doing this type of development was that there was very little change in the low-level NT kernel. I actually don't think this is a bad thing; going from XP to Vista was a breeze because nothing about the driver APIs changed in the slightest, and Microsoft even provided a bunch of new filesystem examples with the Vista DDK.