Just a quick how to post. When you do more and more remote management with PowerShell it may be necessary for you to quickly check if you run Full Server or Core or Nano. And unless you never logon locally to the box you and you only managing it via PowerShell then you may be not very sure if it is running Full Server, Minimal Management Interface, Core or Nano. There is a ServerLevel registry key available starting from Windows Server 2012, and quick look up for its value will answer this question:
dir 'HKLM:\SOFTWARE\Microsoft\Windows NT\CurrentVersion\Server\'
Sample output you may see in case of Nano Server:
Another use case for this key is when you writing a script and need to adjust its behavior depending on whether it is being executed on Full Server, Core or Nano.