I have downloaded Java 6 Update 14 installed on my PC. Previously I had Java 6 Update 7 installed. I would like to know that what are these updates and what features are added in every update? Do new API's come in with every update?
There's a link on the release notes page that explains the security baseline and its use in detail: http://java.sun.com/javase/6/webnotes/family-clsid.html As for the Olson data, it's simply a compilation of information about the world's time zones, like uniform zone names, UTC offsets, DST applicability etc.
Nothing a typical Java developer need be concerned about; that is about the baseline and timezone db versions.