Components
Components are the basic building blocks in Jef. Some examples of components are the job list, service request and standard menu components.
Modules
Before a component can be used in the website, a module must be defined. A module is an instance of a supplied component configured in a specific way. For example, to create a job list on your website you will need to define a module using the job list component, and choose which job fields and/or links to include in the job list.
Some components do not require configuration (such as the standard menu and HTML components) and are predefined as modules.
Page Templates
A page template defines the basic layout, theme and default modules to use for pages that use the template. Normally, most pages on your website will conform to the same basic layout, and will contain the same page header and footer. So, you would define the header and footer for all the pages in a single template.
As part of the template, you can also define the default spacing between modules in the various zones for the template's layout.
Further information: