How joyful is the one whose transgression is forgiven, whose sin is covered!-----Psalm 32:1
Webster's dictionary defines "happy" as; "favored by circumstances." It defines "joy" as; "a very glad feeling."
I believe that "happiness" is a product of what happens to us personally, by or through actions, words, feelings, etc. And our emotion of happiness can leave us as quickly as it came through the very same venues of actions, words and feelings.
However, I feel like "TRUE JOY" is an emotion that only our Heavenly Father could place in the deep recesses of our being, and He gives us that "TRUE JOY" when we come humbly before His throne of Grace, confessing our sins to Him and accepting His FOREVER, ABIDING LOVE in the form of His One and Only Righteous Sacrifice, the Lord Jesus Christ. Then we experience that TRUE JOY! A feeling that goes much deeper in our being than happiness ever could or ever will.
I believe that ONLY those who have called upon the name of the Lord experience "TRUE JOY." Unbelievers may experience the fleeting feeling of "happiness" but will ONLY experience "TRUE JOY" when they give their hearts to the Giver of Eternal Life, Father God. Come to Him NOW, He's waiting!