What is the difference between a psychic and a medium?

A psychic can read from your aura, this is the biomagnetic field that surrounds all things, and is more energetic around living things, the aura will contain trends etc within its vibration.

A medium or should I say a spiritualist medium is somebody who receives messages from the spirit of somebody who crosses over into the spirit world.

These messages often have things that only the sitter and the spirit would know, also guidence and messags of love etc are given. a medium can also pick up on psychic energy as described above. so as the saying goes you can be a psychic but not a medium, but you can be a medium and a psychic.