A Device Package is the elementary toolkit that will enable you create a Client Package (i.e. an application installer) for a given device.
A Device Package comprises a generator that allows you to create a portable package on your device. The Device Package configuration is specifically designed to fit in a particular handset or a device platform (MIDP, Symbian 60, etc.).

Workbench Developer is responsible for creating a Client Package from a specified Device Package given that you provide the project to be packaged as an application.

The resulting Client Package is an installer for your device. Additionally, Client Packages can contain local (client-side) scenes and resources required by the application. The following diagram describes the basic process from Device Package import to Client Package delivery.