Since Windows 8.1 Microsoft compiles system utilities against NT 6.0 kernel.
Until Windows 8.1 Microsoft has compiled system utilities against NT 5.1 kernel so this is a major move.
Windows 8.1 utilities can no longer run on Windows XP !
I suspect this move is a consequence of ending support for Windows XP on April 8, 2014
(Windows 8.1 official release date was October 17, 2013).
All Windows system utilities from Vista, Windows 7 and Windows 8 could run also on Windows XP which has NT 5.1 kernel.
Developers used this fact to implement functionality and support for Windows Vista and later under Windows XP. An example is implementing support for Windows BCD in Windows XP in a dual-boot system with Windows Vista/7/8 (bcdboot.exe and bcdedit.exe utilities until version 6.2.x.x could run without problems in Windows XP).
Windows kernel versions:
Windows XP - 5.1.x.x
Windows Vista - 6.0.x.x
Windows 7 - 6.1.x.x
Windows 8 - 6.2.x.x
Windows 8.1 - 6.3.x.x