For feature-by-edition breakdowns, see the documentation and this blog post. There are no deprecated engine features and no breaking changes, but there are three database scoped configuration options that have been discontinued. The What's New page has summary information about all the changes, and the Release Notes contain more details and known issues. This internal database version is far less likely to change after GA, but it's possible the internal database version of the latest builds of SQL Server 2017 is 869, but at GA it was 868. Database version is indicated below in the DB Version column – helping to makes it clear that you can't take a backup from CTP 3.2 and restore it on CTP 3.0, for example. In some build lists you may have seen release and build dates published, but something that always felt missing was the internal database version, which can be important because it is impossible to restore a database from a higher db version to a lower one. If anything you should be on the latest cumulative update. I really wish they could have just made that part of setup, but timing didn't work out I hope I don't come across any RTM bits at any point in the future. Along with it came an important servicing update ( GDR1 – 4517790) which should absolutely be installed in every environment. SQL Server 2019 became generally available on November 4th, 2019.
