The mental consciousness adopts a particular standpoint or view of existence and blocks out other options as irreconcilable. The overmental consciousness can recognize these different standpoints while at the same time seeing that they are all part of a unified reality and thus, ultimately compatible to one another at some level.
The mental viewpoint therefore sets up opposites and creates a more or less black and white scenario where if one is true, the other must be false. If the essential reality of the universe is impersonal, then this viewpoint says that the personal view of the universe is wrong.
The overmental consciousness can see the truth of both aspects, and thus, can reconcile the Nirguna Brahman, the Divine Existence that is impersonal and formless with the Saguna Brahman, the Divine Existence having Personality and form. They complement one another, are simply correlatives to one another.
The process followed by the mental consciousness is seen clearly in the Taittiriya Upanishad sequence whereby the student/disciple is asked to meditate to find out the truth of existence and comes back with one fixed idea after another as the process goes through successive rounds. Matter is the reality, but upon further reflection it is the life energy. Going further still, the seeker finds it is the mind. But this is not sufficient, it is the consciousness consisting of knowledge, and eventually that of bliss. In each case, the statement is both categorical and eventually overturned as the next option comes into view.
The overmental consciousness would see that these 5 are actually gradations, layers or phases that all coexist, have their own reality and their own inter-relationship. There is a complex multiplicity that includes all these gradations.
reference: Sri Aurobindo, The Life Divine, Chapter 28, Supermind, Mind and the Overmind Maya