Unconscious means "without awareness," "without conscious control," "involuntary." A conscious person has some control of his faculties; an unconscious person may be in a coma, suffering from shock, or asleep. As a noun, the unconscious is a term in psychoanalysis meaning that part of the mind containing the psychic material of which a conscious person is unaware. Unconscious has an additional meaning of "not intended" "not planned": "My failing to recognize you was an unconscious slight." Much less used, subconscious has many of the meanings listed here for unconscious but is specifically applied to unreportable mental activities, to one's mental processes of which he is not aware: "The subconscious thoughts and impulses of thousands of characters have been portrayed and plundered in modern novels and plays."
Dictionary of problem words and expressions. Harry Shaw. 1975.