The Genome Appliance is the center of development in the Genome environment. In a nutshell it is the self-contained provisioning, configuration and artifact store. For this reason Genome Appliances are generally not considered volatile.
As all other machine types it is designed to work as both a "baremetal" and virtual machine. The main resource requirement that distinguishes this machine type is disk space, which is a function of the amount of bits imported to cobbler.
There was a time when Genome Appliances were able to be created via genome-bootstrap. This led to several "chicken and the egg" sorts of problems. For this reason the method for provisioning Genome Appliances was switched to RPM.