The Project map is generated automatically from you model based on the storeys, elevations, sections, details, etc., that you place.
You must manually control the scale, layers, pen set, model view options, graphic override, etc., for each of the view points in the Project map.
The View Map is completely customisable by you.
You can have as many (or as few) views for each storey, elevation, section, detail, etc., as you want.
You also set the scale, layers, pen set, model view options, graphic override, etc., for each view (you can change these in 'view settings' at any time) so that you do not manually have to set these.
These views can then be placed on a layout (with the 'drawing' tool) and they will always have the correct view settings so will always look the same.
For example this allows you to save pre-set views in the view map for your floor plan, site plan, roof layout all from a single storey view point in the project map.
One click and you have the view you want rather than manually changing all the settings.