Software Appliance

A software appliance is a software application that might be combined with just enough operating system (JeOS) for it to run optimally on industry standard hardware (typically a server) or in a virtual machine.

Virtual appliances are a subset of software appliances. The main distinction is the packaging format and the specificity of the target platform. A virtual appliance image is designed to run on a specific virtualization platform, while a software appliance is often packaged in more generally applicable image format (e.g., Live CD) that supports installations to physical machines and multiple types of virtual machines.

Installing a software appliance to a virtual machine and packaging that, creates a virtual appliance.