Many analysts, including yours truly, were somewhat surprised to see how few changes were made between Windows 8 Consumer Preview and Windows 8 Release Preview. Normally, at this point in the process, you'd get a "Release Candidate" which would be, as the name implies, feature-identical to the final product, barring any major revelations during testing.
This time, thanks to Microsoft's blog, we know about upcoming features in the final release. This includes a new flattened design for the "desktop" interface in Windows 8, which serves as the replacement for running legacy Windows 7 apps, as opposed to the tablet-friendly, newfangled Metro-style apps, with their tiles and simple, touchable design. Despite the lack of many new, marquee features in Release Preview, Microsoft claims that hundreds of visible changes and tens of thousands of internal coding changes have been introduced
