In the past, , @CSD would return the service pack that your OS was on. Now with Windows 10, Service packs are replaced with bi/annual updates, like 1703, the creators update.

The version of Windows 10 can be obtained via the registry at:
HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Windows NT\CurrentVersion\ReleaseID

For Legacy Scripts, I would like to suggest that @CSD also return the ReleaseID for Windows 10.