They are synonymous, but by euphony "joyous" is more exuberant-sounding. "Joyful" is rather restrained-sounding by comparison.

Joyful is generally used to describe the way a person feels, and joyous is generally used to describe things like events and places. So you would be more likely to hear a joyful child than a joyous child, or a joyous occasion than a joyful occasion.

Hi.

I think joyful is used to mean that something or someone is full of joy and can be enjoyed, an adventure for example. Joyous is used to describe the person who is into joy and can enjoy things, it's like a personal characteristic.

She is a joyous young woman who enjoys joyful events.

SurferHi. I think joyful..

I should've italicized, Joyfol and joyous. Sorry.