etad eva hi vijñanam
na tathaikena yena yat
When one no longer sees the twenty-eight separated material elements, which arise from a single cause, but rather sees the cause itself, the Personality of Godhead — at that time one’s direct experience is called vijñana, or self-realization.
The difference between jñana (ordinary Vedic knowledge) and vijñana (self-realization) can be understood as follows. A conditioned soul, although cultivating Vedic knowledge, continues to identify himself to some extent with the material body and mind and consequently with the material universe. In trying to understand the world he lives in, the conditioned soul learns through Vedic knowledge that the Supreme Personality of Godhead is the one supreme cause of all material manifestations. He comes to understand the world around him, which he accepts more or less as his world. As he progresses in spiritual realization, breaking through the barrier of bodily identification, and realizes the existence of the eternal soul, he gradually identifies himself as part and parcel of the spiritual world, Vaikuntha. At that time he is no longer interested in the Personality of Godhead merely as the supreme explanation of the material world; rather, he begins to reorient his entire mode of consciousness so that the central object of his attention is the Personality of Godhead. Such a reorientation is required, since the Supreme Lord is the factual center and cause of everything. A self-realized soul in the stage of vijñana thus experiences the Personality of Godhead not merely as the creator of the material world but as the supreme living entity existing blissfully in His own eternal context. As one progresses in one’s realization of the Supreme Lord in His own abode in the spiritual sky, one gradually becomes disinterested in the material universe and ceases to define the Supreme Lord in terms of His temporary manifestations. A self-realized soul in the stage of vijñana is not at all attracted by objects that are created, maintained and ultimately destroyed. The stage of jñana is the preliminary stage of knowledge for those still identifying themselves in terms of the material universe, whereas vijñana is the mature stage of knowledge for those who see themselves as part and parcel of the Supreme Lord.