Why the difference between the Extension list and the Plug-in list
On my Extension list I can see -
Java Console 6.0.22 Enable Java Console 6.0.23 Enable Java Console 6.0.24 Enable Java Console 6.0.25 Disable
The old versions have been disabled.
On the Plug-in list I can see -
Java Deplyment Toolkit 6.0.250.6 Java Platform SE 6 U25
If I check via the Control Panel I appear to have only
Java 6 Update 25 installed.
Why the discrepancy?
Why do I still see references to older versions, and presumably not on the computer any more, shown on the Extensions list?
Opaite Mbohovái (3)
Java doesn't cleanup after itself when it updates to a new version. I get around the "accumulation" of Java Console extensions by not doing an update; I uninstall the older version and install the new version when a new version becomes available.
That link was most helpful. Opening FireFox as an Admin, something I had never thought of, allowed me to remove the dead wood from the 'Extensions' display.
Previously, the only way I could be certain exactly what was actually available was by visiting Control Panel ... Programs and Features
Thanks to both of you for your interest.