Neurotic contents can be integrated without appreciable injury to the ego, but psychotic ideas cannot. They remain inaccessible, and ego-consciousness is more or less swamped by them.
Jung establishes the defining structural difference between neurosis and psychosis: psychotic contents, unlike neurotic ones, overwhelm the ego and resist integration, originating in the collective unconscious rather than personal history.
, The Archetypes and the Collective Unconscious, 1959thesis