What there saying is the Windows 8 Enterprise Evaluation isn't the full RTM its a version which u can try for free like a DEMO, If you have the RTM MSDN iso then you have the final version of windows 8.
Ok. I can see that the person from Microsoft has removed his reply after I asked there... But Windows 8 Enterprise 90day eval. is using build 9200 also, so it's the RTM build.
RTM (Release to Manufacturing) must not be mean it's final! In many cases in the past, the final build were different from RTM, which may or may not will be shown in it's extended build number while the main build number still could be the same as for the RTM. In the Windows 8 case: 9200! The "Grace" Period manufacturers having for to develop and deploy their own changes to the OS is needed for them to have their products ready for to work on the date of public appearance in the shelf's. But MS will not sleep at that time and also do last changes on the OS before giving it out to public. And even than, MS will carry on to work on Bug fixing, enhancements and more after public release.