You might want to start here: Database New Features Guide - Contents
This section talks about just DG new features: Oracle Database 12c Release 1 (220.127.116.11) New Features
Keep in mind that "12c" is not a version number. Its just a label. The document I linked contains info on 18.104.22.168 and 22.214.171.124 but you may also be talking about 126.96.36.199 which is in a different book.