The Imaginary (n.) is (if viewed through the game of chess) the way different pieces are shaped and characterized by their names (king, queen, knight) which are just as easily replaced by a different imaginary (messenger, runner, or whatever).
The Imaginary (n.) is concerned with the ego whereas the symbolic is concerned with the subject.
The Imaginary (n.) is concerned with the mirror stage and marks the movement of the subject from primal need to 'demand'. Whereas needs can be fulfilled, demands (to quell anxiety by making the other part of itself) are, by definition, unsatisfiable.
The Imaginary (n.) is primarily narcissistic even though it sets the stage for the fantasies of desire.
The Imaginary (n.) serves an assimilating, reflecting, doubling and duplicating role (in contrast to the symbolic which serves a differentiating role).
The Imaginary (n.) is the fundamental narcissism by which the subject creates images of himself and ideal object of desire.