Joy is a deep inner peace and confidence in the Lord. Happiness on the other hand is fickle, dependent upon our circumstances. Joy recognizes that pain and suffering are part of life and therefore it is not contingent on circumstances. Because joy comes from Him who never changes, joy is ever available no matter what befalls us. It is a fruit of the Spirit. When we are filled with the Spirit and following in His steps, we exude the joy that He freely gives.