Joyful is known to be an emotion that is used when you need to describe how a person is feeling at the present time. This is considered to be a positive trait because this shows that a person is happy. Joyous is a term that is used more when describing an event that has taken place. For example, you will use the word joyfully when you are describing your emotions.
Then, you will use the word joyous when you are describing the event that you have attended. It is important not to become confused between the two to ensure that you will use the words properly whenever you need to do so.