How does a Theophany differ from a Vision or Apparition?
Are you asking about the meaning of the words?
A Theophany is a direct manifestation of God(in word or form) to human beings.
An apparation (or supernatural vision) is when a human being perceives something that is usually not able to be perceived.
I suppose you could argue that that a Theophany is a subset of Apparation, however precision demands two different words I think.
This is a “spookey” topic to me.
a theophany is an experience of the presence of God, without necessarily involving any of the senses - hearing, sight, touch, smell, sound. An apparition is just that, a vision of a heavenly being, usually Mary or a saint, although Catherine laboure and Sr. Faustina reported seeing and hearing Jesus himself. Sometimes an apparition is accompanied by hearing words or a message, or music, or smell as of roses etc. Others have reported “locutions”, hearing a message without a vision.