Conceptual art was about social or psychological language structure at that particular moment in time.
Mine always invloved the question of the audience, its perception of itself, and of performance in the act of perceiving.

Reductionist structure-conceptual art, as well as minimal art, was interested in what one calls reductiveness. One principle was that less is more. The idea was to reduce things-ideas, surface, content- to the point where they seemed to be blank or were tautologies, or had no obvious content in terms of representation or seemed not to be saying anything. Behinde the apparent blank surface was often an incredible complexity.

what was left was the phenomenological presence of the here and now of reading and seeing art in an architectual environement.
-Dan graham