A while ago, Windows 8 Consumer Preview was released, the first version of the new Windows 8 OS to be publicly released by Microsoft.
The differences between the two will be major however. Release Preview can be considered the final version of the Windows 8 operating system, as it includes all possible features.
Just like Windows 7, Windows 8 Release Preview will probably work for a limited time.
The final version of Windows 8 OS is expected to arrive on the market in October. So, until it does, we will have the entire summer to test the newest Windows version. However, we do not expect Microsoft to also provide the tablets version or the version for devices with ARM architectures.
Computer manufacturers will most likely get the new Windows 8 OS much sooner so they can work on creating drivers.