I just checked with Culture Explorer 2.0, there is a distinction between Windows-only cultures and installed cultures, as well as .NET Framework cultures (which, at least on my system, only contain language-only cultures). All of these are supported by the CultureInfo class (and RegionInfo, NumberFormatInfo and so on).
I also ran it on Mono (on Linux), it's roughly the same, with the .NET Framework cultures and the Windows-Only cultures missing, but the Specific and Neutral cultures are there. RegionInfo.CurrencyNativeName
seems not to be implemented in my Mono version though, so it crashes when selecting any culture.
Unfortunately, Culture Explorer 2.0 is currently not available from anywhere (was on gotdotnet.com), I downloaded it some time ago. It's a handy tool for such things. You may have luck to find one in some archives.