In the bible Jesus used the word gladness to refer to physical joy. In the hot summer when you are very thirsty and you drink some soda from the refrigerator you feel so good. But after one minute the feeling leaves. Actually joy and gladness is very fleeting. It is only temporary.
Happiness is something that is long-term.
Permanent rather than temporary. The world of happiness lasts eternally. That is the meaning of a happy life. Joy is more temporal and happiness is more permanent. Father wants to create a world of happiness.