Only 18 years after Apple. Don’t ever accuse MS of being hasty.
Color me confused by your comment.
Apple built OS X on BSD Unix, not Linux, and the Unix kernel they used ("Mach") is running the operating system, with the Mac GUI on top.
Microsoft is incorporating a Linux kernel as part of the Windows Subsystem for Linux -- but the Windows 10 "NT" kernel is still running the operating system.
Granted, it would be REALLY cool if Windows were to scrap the NT kernel and re-implement Windows as a Linux kernel running the operating system, with a Windows GUI on top. But that's not happening.... yet :-)