The only noticeable difference we could see is the dock, it looks more different than that of OS X Mavericks.
OS X Yosemite is expected to have a more significant redesign than Mavericks, which focused on refinements, as Apple continues to bridge the gap between iOS and OS X. We will have more details on OS X Yosemite as the WWDC keynote unfolds.
As usual we will keep you updated with any progress at the WWDC 2014 event, stay tuned.