Jay...
a 'module' is the old V4 term for a 'product' in V5.
When you buy CATIA, you either buy individual products (or modules), or you can buy a configuration of pre-packaged products (and save a couple $$$).
As a V5 user, you're right - a 'module' is kind of like a workbench. Licenses are also based on products(modules) or configurations.
....Jack