There’s a difference. 

Happiness stems from without, from something good or a string of these happening around you. Because happiness comes from other people or circumstances, the opposite is also true, it can be destroyed by the same. 

Joy comes from within. It is a state of being, where no matter what happens, you enjoy being alive, enjoy where you are. Everything may not be perfect, people may be disappointing you all around, but that doesn’t diminish the joy within. Joy is not a bubble, it can’t be burst. 

This is what we aim for, joy, that the outside will not determine our inner status.