A bin file contains clips of audio and video you will edit and assemble into a finished program. A program file is created to sequence the playing of your audio and video clips. It gives timing information. Think of it as your final production. It's what you play to see your finished production.
Media files are the actual digitized media.
These are huge files stored on the atached large disk array. You will largely let the Media 100 program handle their creation and use. You'll keep your projects, programs, and bins here. Your actual media files will be kept on the external disk array. You will save projects, bins and programs to your own folder on the internal hard disk of the station.