What's only seen/used in one view or the other?
Siblings. A Map view is the map of the contents of a single container. As such all items on the map are siblings. Items at the same $OutlineDepth but inside different parent containers cannot be seen in the same map. Thus, no matter how big the map view window is expanded or zoomed, it will never show notes like 'Context' and 'How this TBX was created'. This is because whilst the latter are the same $OutlineDepth as note 'aa' they are children of a different parent container and thus not siblings of 'aa'.
Separators. These are only seen in Outlines. They are not drawn on a map. Separators may have a title (as here) if the note is given a name, otherwise the separator is simply a line drawn in the outline where a note would otherwise appear. A separator is in fact a fully functional note - the separator display mode can be toggled off/on via the 'Separator' tick box on the note create/rename dialog. Incidentally, if a separator is toggled back to a normal note, it will appear on the map as well! A separator can also act as a container. Making a map container a separator can be a way to hide map content, removing the separator flag (via outline view) will return the content to the map.
Adornments. These are map-only objects. They show up on a map although always behind all notes. More on adornments follows below.
Notes inside containers (nested notes). Containers (and agents) show a small part of their nested contents via their 'viewport'. In general, any descendant notes/containers (i.e. at a lower $OutlineDepth than the current one) are invisible to maps unless within the scope of a viewport.
Link lines. Not shown in the illustration, Tinderbox links are only shown in map views (assuming a link type has not had visibility toggled off).
Otherwise we have notes, containers (notes containing notes) and agents (in this context consider agents as just another sort of container); all these objects are shown on both outlines and maps.
Next… What is OutlineOrder?