More information at http://www.morgantechspace.com/2017/09/how-to-find-windows-os-version-using-powershell.html
(Get-WmiObject win32_operatingsystem).version
Output:
6.1.7601
(Get-WmiObject Win32_OperatingSystem).Caption
Output :
Microsoft Windows 7 Ultimate
Get-WmiObject Win32_OperatingSystem | Select PSComputerName, Caption, OSArchitecture, Version, BuildNumber | FL
PSComputerName : CATCHYCOMPUTERNAME
Caption : Microsoft Windows 7 Professional
OSArchitecture : 64-bit
Version : 6.1.7601
BuildNumber : 7601