How can I tell which version of Windows 8 I am running? Standard, Pro, Enterprise, or RT?

I suspect it is the standard edition.

I have Pro and it shows as Windows 8 Pro as per the image below.

Windows 8 Pro

Alternatively, you can try the following from the command line:

systeminfo | findstr /B /C:"OS Name" /C:"OS Version"

Windows version from command line

To complement the other answers, I have Windows 8.1 Basic Edition, and the System Properties shows just "Windows 8.1".

System Properties Windows Edition - "Windows 8.1"

In PC Settings -> PC Info, the same information is available:

PC Settings Windows Edition - "Windows 8.1"

This should complement the screenshots of the other editions shown in the other answers.

It will tell you on the System properties screen (WinBreak). I'm running Win 8 Pro and it reflects that:

enter image description here

If yours just says "Windows 8" then I would say you are running the standard version.

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