Microsoft has implemented a few modifications in 8.1 build 9477
This version does come, however, with some slight changes on the Start screen, including different colors and icons for the Mail and Help & Tips apps.
The font also appears to be bigger, but this could actually be a modification made to the Chinese version. Build 9477 is currently available in Chinese language only, but with a few tricks, switching to English is also possible.
Otherwise, Windows 8.1 remains practically unchanged, as Microsoft probably spends a lot more time trying to improve the overall performance of the app.