The Version table provides details related to the release that this issue/RFE will be addressed.
Unresolved : Release in which this issue/RFE will be addressed. Resolved: Release in which this issue/RFE has been resolved. Fixed : Release in which this issue/RFE has been fixed. The release containing this fix may be available for download as an Early Access Release or a General Availabitlity Release.
There are no appreciable differences between these files. It may be a better idea to have a base "posix" class and create new files for exceptions to the base behaviour. (e.g. UNIXProcess.java.solaris)
Here's a preview of an attempt to merge all 4 UNIXProcess.java.[linux|bsd|solaris|aix] variants into common source:
It's not finished yet (OS resolving code missing - only for Linux currently, but it resembles the logic currently present in jdk9-dev - just refactored)