Vastly more advanced. The NT kernel was designed by Dave Cutler (of VMS fame). When work on NT started, it was simply beyond what PCs could do: the design included every high-profile buzzword from the minicomputer world, as well as portability across CPU architectures and a hardware abstraction layer. (Originally NT was supposed to be OS/2 3.0.)
NT was one of Microsoft's most brilliant long-term investments. It delivered the true Unix competitor they needed in the '90s, and the kernel is still there in Windows 8 with no urgent need to replace it.
If you ever have a chance to read the book "Showstopper" by G. Pascal Zachary (and haven't already), do it. Awesome book about Cutler and the creation of Windows NT.
NT was one of Microsoft's most brilliant long-term investments. It delivered the true Unix competitor they needed in the '90s, and the kernel is still there in Windows 8 with no urgent need to replace it.