Happiness and joy are certainly something we all desire. So what is joy and what is happiness? Is there really a difference, biblically and otherwise?
As a practical matter a happy person is joyful and a joyful person is happy. So as a practical matter the two words are interchangeable in most circumstances; yet, one may be preferred to express a state of being over the other depending on the circumstance and conditions.
In a very simplistic sense happiness is a consistent state of pleasure about, with, in the presence of or in anticipation of someone, something or someplace that one considers a good thing. And joy is a particular instance of relatively intense recognition of that pleasure. This recognition may manifest through outward expression or inward sense and mustering up of strength to be and do that which is good or not be and do that which is bad.
In this sense, happiness is foundational to joy. This means one cannot have joy without happiness and one cannot have happiness without some degree of joy.
Both happiness and joy occur at various degrees for a given person overtime. Also, both joy and happiness occur at various degrees across people. Both happiness and joy can be circumstantial with regard to intensity.
In the Bible, the word blessed is sometimes associated with happiness. The word blessed, however, need not be about something one considers a good thing although it is a good thing. For example, a child is certainly not happy or joyful when a parent disciplines that child. But that child is being blessed by that discipline as it prepares the child for better living. Indeed, parents sometimes say if you don’t stop that I am going to bless you or give you a blessing. The idea is that the discipline will result in the child more apt to have a happy/joyful life. So it is with God concerning the children of God.
In conclusion, do not get caught up such small matters as differences that make no difference.
Reference: Is There A Difference Between Joy and Happiness