Allegedly, on or about 05 February 2014, Paul Smith sent:
I would like to install F20. Is there some iso file more recent than the one made available at the release date of F20? If so, where can one download it?
The release ISO is the release ISO, it doesn't get updated revisions. Any updates of the packages, are done after installation. They don't make newer ISOs with updated packages.
There are *different* ISOs, which would probably all be built from the same packages, the differences between them being the sets of packages included in it - a release for a Gnome installation, an alternative for a XFCE release, et cetera.