From Wikipedia...
A scene graph is a collection of nodes in a graph or tree structure. A node may have many children but often only a single parent, with the effect of a parent applied to all its child nodes; an operation performed on a group automatically propagates its effect to all of its members. In many programs, associating a geometrical transformation matrix (see also transformation and matrix) at each group level and concatenating such matrices together is an efficient and natural way to process such operations. A common feature, for instance, is the ability to group related shapes/objects into a compound object that can then be moved, transformed, selected, etc. as easily as a single object.
The DALi scene graph consists of objects (nodes) such as images, text and buttons.
Views are also effectively nodes which receive input (touch events), and act as a container for draw-able elements (which are also nodes), and other views.
A View is the primary object with which DALi applications interact. Views can be visible (UI component) or invisible (a camera view).
A DALi application uses a hierarchy of View objects to position visible content. A View inherits a position relative to its parent, and can be moved relative to this point. UI controls can be built by combining multiple Views.
The Stage is a top-level object used for displaying a tree of views.
A View must be added to the stage to display its contents.
Note: The term 'View' has now replaced the term 'Actor'.
The following example shows how to connect a new view to the stage:
View view = new View();
Stage.GetCurrent().Add(view);