Smile is a sign of joy, while hug is a sign of love. Laughter on the other hand is a sign of inner happiness. None of them are at the level of mind or intellect. All come from within the heart. They are only the gradations of your expressions of your happiness. It is said you are incomplete in your dress if you are not wearing smile on your face. Hug comes next and laughter the last. Laughter is like an internal jogging and has benefits like that of doing meditation. But be careful we must know when not to laugh. The most difficult is to laugh on oneself

 (Disclaimer: The views expressed in this write up are my own).