I'm using Windows 8.1 but TCC says
TCC 15.01.52 Windows 8 [Version 6.2.9200]
and cmd.exe says
Microsoft Windows [Version 6.3.9600]
Windows bug / unfeature. TCC is querying the Windows GetVersionEx() API, which is returning the wrong info. Microsoft said the GetVersionEx API was deprecated for versions of Windows after 8.1; apparently they decided to accelerate the process and make it useless in 8.1 as well.
CMD is probably using the new version helper APIs, which are only available in 8.1 and later. (Must be nice to be able to write something that only has to run in one version of Windows ...)