Hello Lee,
> Can someone please clear this up for me.
Will try to do so 🙂
> What is the difference between 14.X and 19.X when both seem current?
You can see the feature comparison here:
JUNOS Feature Comparison
In general, you can find all JUNOS release notes for EX4300 here:
EX4300 release notes
As it is with every vendor, new major releases (18.1, 18.2, 18.3, ...) bring new features and bugfixes. Maintenance releases (R2, R3) will bring bugfixes and sometimes new features, and Service releases (e.g. R2-S1, R2-S2) will bring bugfixes only. And all of them can include security fixes.
Please note that JUNOS releases have End Of Life dates, these are important if you have service contracts and need to open a JTAC case. You can find the EOL dates here:
JUNOS EOL dates
As you can see, 14.1X53 is already End of Support. So JTAC would not accept new Service Requests for platforms with this release installed.
If you want to download major or maintenance releases, choose "JUNOS" at the download site. If you want to download service release, choose "JUNOS SR" (please see attached picture).
Hope this helps.