I would say feeling calm and peaceful. Sometimes I feel in a really great mood and I think THIS is what normal feels like. But then I worry... do I feel peaceful and calm? No, I feel I urgently need to learn a language, learn to play violin so I can write music, learn to paint, talk to everyone about my great ideas. But I can't because I can't keep a thought long enough to make sense of it. That's how I, personally, know the difference.