Discernment, discrimination, perception, penetration, insight, acumen are comparable when they denote keen intellectual vision. All imply power to see below the surface and to understand what is not evident to the average mind.
Discernment stresses accuracy (as in reading character or motives or in appreciation of art).
Discrimination emphasizes the power to distinguish and select the excellent, the appropriate, or the true.
Perception implies quick discernment and delicate feeling.
Penetration implies a searching mind and power to enter deeply into something beyond the reach of the senses.
Insight emphasizes depth of discernment or of sympathetic understanding.
Acumen suggests characteristic penetration and keenness and soundness of judgment.