Question about OpenJDK version numbers

[Attila-Mihaly Balazs]

Hello everybody,

I would like to know the correspondence between OpenJDK version numbers 
and Sun/Oracle JDK version number and my search turned up empty. For 
example java -version on my Ubuntu box says: java version "1.6.0_23" but 
the Oracle JDK is up to 6.29. Is there a way to know if all features / 
fixes from a particular version of Oracle JDK are present in a given 
version of OpenJDK?

Best regards,
Attila Balazs