Here is a chart to explain the results.
You can also read registry values and environment variables. I have some examples at work, but I'm on vacation this week.
The .vi from unclebump doesn't work on Windows 10 Pro (at least for my login). Easy to fix: add "KEY_READ" as the access type.
I'm having similar issues with other apps accessing the registry, too. I guess it was a "security improvement".
Another method of getting the OS rev: Use a Property Node, select class to "VI Server/Application", and pick "Operating System/Version Number". The text is different, so not a direct replacement. "Operating System/Detailed Name" is the same as the registry method (at least on Windows 10 Pro). I didn't test outside Windows, but expect it to work.
[Of course, we can never trust new OS updates to behave exactly the same, so be careful to test.]