In my understanding, Joy is the emotion of overt happiness. It elicits silly behavior, celebratory vocalisation, laughter, and hugging.

Happiness is the state of satisfied being devoid of feelings of remorse, emotional pain, grief, or anger. It is a state that accepts joy, that provokes appreciation, gratitude, and satisfaction. It is a generally open and creative state, that gravitates toward the positive.

It is possible to maintain a state of happiness amid unfavourable events and conditions if your mind and actions are guided by a moral framework, and even to maintain a sense of happiness through hardships and injustice if you have built the philosophical structure to separate your mind and sense of self from your circumstances.

Happiness is being content. You can be a generally happy person.

Joy is more exuberant - but more fleeting. You can't be a person constantly experiencing joy (except maybe as a bipolar during their manic phase)

I think in short:

- big things (e.g. someone dies) you cant avoid being sad

- small everyday things (e.g. someone cuts you off at the intersection) you have a choice to smile and treat it lightly or go all passive aggressive and spiteful.