What added features in Adobe Photoshop CC 2015 and what's not on CC 2015 that the CC 2014 have; give even 1 features?

Libraries has been updated with all-new features for2015.

• Browse Adobe Stock for stock images and automatically add them to your libraries. 
• Use Linked Assets in Libraries to keep all your graphics up to date when an edit or update is made to them.
• Use Share Link to publicly share individual assets or entire libraries with others.

Artboards lets you make multiple layouts of different sizes in a single document, and the new Device Preview shows how designs and interactivity will look and adapt on mobile. The Healing Brush, Spot Healing Brush, and Patch tools have been turbocharged with Mercury Graphics Engine enhancements, so you get results up to120 times faster than you would if you were using CS6. And be sure to check out the new Photoshop Design Space (Preview Technology), a streamlined experience optimized for designing websites and mobile apps.

Think of CC2014 as a clean slate version that doesn't have some of the "features" that were part of version14 (cc2015). (Oil Paint filter was removed, as were flash-based plug-ins like Mini Bridge, etc.) I suggest that you read more, http://prodesigntools.com/whats-new-features-adobe-cc-vs-cs6.html