"Revisor enables you to customize and compose your own installation and live media. It does so by presenting you a GUI with all options, and a CLI for the more advanced users. Features that Revisor has vary from customizing the packages available during the installation and/or installed on the live media, to fully customizing the desktop environment for the live media.
Installation media would be the media you use when you install a machine to run Fedora (the CDs and DVDs the Fedora Project releases every 6 months). You cannot do anything with installation media other then install a system to run Fedora.
Live media on the other hand allow you to run Fedora, without the need to install it on your system first. Actually, the operating system is installed on a CD, DVD or USB Thumbdrive, and you let your computer boot that operating system."