Happiness depends on what happens to us; joy depends on what we choose to do. Of course the two are not unrelated, but the first has more to do with things that are largely beyond our control; the second is more in our hands. We can actively enjoy or rejoice, but we can’t enhappy or rehappy. 

The word joy comes to us from the French joie from the Latin gaudere (to take pleasure in), which has also given us the Italian gioire (to rejoice).

There is a link between ‘u’ and ‘l’ (eg. the French ‘saumon’ is spelt ‘salmon’ in English), and between ‘i’ and ‘l’ (compare ‘blanc’ in French with ‘bianco’ in Italian). Considering also the proximity in sound and function of ‘-ir’ and ‘-er’, it seems likely that: the French jouir (to enjoy), jouer (to play) and jolie (beautiful) are related to ‘joy’; that the Italian gioire (rejoice) has a connection to the French gloire (glory); and that there might therefore also be a link between the Latin words gaudere (to take pleasure in) and laudere (to praise). 

In Chinese there are many words for both happiness and joy, but 幸福 (happy) is comprised of the characters for good fortune and blessing: things that may or may not be bestowed upon us. By contrast, 乐趣 (joy) is comprised of the characters for pleasure (or music) and interest (or delight), things that in English we typically use with the verb ‘take,’ which suggests they are more dependent on our action. 

Our circumstances and what others do to us may be unpredictable; but what we take an interest in and where we derive pleasure; whether or not we choose to play and look for beauty; what we honour and celebrate … these are things we have some control over and result in a joy that is quite independent of happenstance.