The "Full" Jamroom 4 download (called "Jamroom 4 Core") consists of ALL of the Jamroom files needed for a new Jamroom install.  This is the version you want to download if you are installing a NEW version of Jamroom, or upgrading a Jamroom 3.x install of Jamroom.
 

 

If you are currently already running Jamroom 4, then easist way to stay current with your Jamroom install is to use the "Jamroom Upgrade Changes Generator" tool:

This tool allows you to download ONLY the files that have changed between the version you are currently running, and the latest Jamroom version available.  Make sure and follow the Upgrade Guide to ensure you upgrade properly