Navigation Service
The NavigationService provides the means to request the navigation to a structure. The NavigationService forwards the request in the form of a presentation request to the Presenter. It is the responsibility of the presenter to get an appropriate interpretation of the structure.
One key aspect of the Navigation Service is its ability to support navigation between different views. In a nutshell a view is a visual representation of a structure within the software.
Navigation
A view might not want to display the entire structure it represents by itself. For example the List does not render its content in full. Instead the view provides a clickable area (e.g a button) which when pressed should take the user to the substructure. This process is called navigation.
The navigation itself in the end is handled by the presenter. The Navigation Service is only responsible for forwarding the request to the presenter.