Hello Kiran,
a "delegated node" represents an included Dependent Object (e.g. TEXT_COLLECTION) in its host Business Object. At runtime, it is replaced by the nodes of the DO.
A "representation node" represents a foreign Business Object (not a Dependent Object) in order to allow you to navigate to that foreign BO via retrieve-by-associations. So it is not an inclusion (like in the "delegated node" case) but only a kind of a reference.
Best regards
Tilmann
