You must be aware that Windows 8 Consumer Preview was released recently. Microsoft also published a theme on its blog post that showcases some of the new desktop theme features available in Windows 8.
Microsoft has revealed in a recent blog post that though Windows 7 themes can work in Windows 8, the vice-versa is not true. In other words, the themes created in the Windows 8 format will not work on Windows 7 platform. The reason for this non-compatibility of Windows 8 themes with Windows 7 is because of a few new desktop personalization features that aren’t supported in Windows 7, and the file format is different.
One of new features is the ability to create and use panoramic themes that extend a single background across two monitors. Some of the other features are namely auto color settings, panoramic theme support, and better dual monitor support in general.
It’s only because of these added features with some changes that Windows 8 themes are not compatible with a Windows 7 operating system. To know more about these features, click here.