The new cadence of more frequent releases (and overall development spirit) got adopted by the SQL Server Engineering team. Beginning with Community Technology Preview (CTP) 2.3 almost every month a new SQL 2016 version was released. For those of you that are not that deep involved in the CTP-hypes I would like to recommend a very good overview page containing the differences and new features contained in every single CTP.
The SQL Server 2016 Release notes page (https://msdn.microsoft.com/en-us/library/dn876712.aspx) provides a good entry point for all the differences and news for single CTP versions:
And even more specific you’ll find the feature changes for every single component: