Surface Pro 2 is the high-end, premium and flagship device which is runs on Windows 8.1. Microsoft has made certain changes to the hardware specifications of Surface Pro 2 as compared to Surface Pro.
Surface Pro 2 supported operating systems
So far as the operating system that Surface Pro 2 now supports, the status is as follows:
Both Surface Pro and Surface Pro 2 devices are optimized for 64-bit versions of the Windows operating system. On these devices, the 32-bit versions of Windows are unsupported.
If you try to install a 32-bit Windows on these devices, they may not boot correctly, whether you try to boot to an image that was applied to the local disk or whether you try to boot from external USB or DVD drive or any media.
Moreover, installation of Windows 8 on Surface Pro 2 devices is not supported. You will need Windows 8.1, since all the device drivers and firmware are written for Windows 8.1 specifically.
Surface Pro 2 is ideal for Enterprise. Surface Pro and Surface Pro 2, both support Windows 8.1 Enterprise x64 and Windows 8.1 Update Enterprise X64 operating systems.
So if you are using Surface Pro 2, you should use Windows 8.1 as the base for custom images. The servicing changes between Windows 8 and Windows 8.1 will not allow the drivers and firmware written for Windows 8.1, to function properly on the Windows 8 operating system.
In short, KB2858199 states that while Surface Pro will support all 64-bit Windows 8 and Windows 8.1, Surface Pro 2 will support 64-bit Windows 8.1 Pro and Windows 8.1 Enterprise only.