Because I happen to be a synesthete, most words and colors seem to have a specific feel to me, and are often followed by a certain image. The word 'joyful' is no exception at all. For me, it has a puerile, innocent feel about it. The image that follows is like an ambient sunset with glimmering patches of light dappling the horizon. It's different from being happy or content because, like I said before, 'joyful' is a bit more naive and childish. It's the difference between watching small children playing at the park - happy - to actually being one of those children - joyful. I hope this answered your question.
