What does SAP mean with "Work center navigation roles" and what is the difference to "authorization roles"?
Work center navigation roles are based on the concept of authorization roles (transaction PFCG). In contrast to authorization roles, which contain a number of authorization objects for authorization purposes, work center navigation roles are only relevant for the navigation in the work center via menu entries.
They display the menu hierarchy/entries in the SAP NetWeaver Business Client (NWBC). The first level is the home page Web Dynpro application (WDA) of the work center (for instance Incident Management). The second level consists of several related links, such as Service Marketplace or Help Portal.
The workcenter navigation roles are defined using the corresponding menu entries in transaction PFCG.
For more details about work center navigation roles you can find in the current SAP Solution Manager Security Guide.