All carry some sense of “not natural, not found in nature.” Something supernatural is “not of this world, spooky” and suggests “nonrational, mysterious forces at work.” Supranatural is a rarer and more technical term, meaning “transcending nature.” Unnatural means “deviating from nature or natural laws,” “outrageous, uncharacteristic of natural feelings or behavior,” and hence often “perverted or evil”; it also means “artificial, contrived, strained,” as in She was wearing an unnatural smile. Preternatural means “beyond or transcending nature and natural laws and feelings” and hence often “exceptional, extraordinary,” or even “unusual.”
