The difference between a psychic, a clairvoyant and a medium are slight.  They are all soul powers but specializes in different ares of human perception.

A medium is someone who is able to channel communication with the unseen world.  In a sense any psychic power is is related to a medium but in a strict medium is dealing with energies that have lingered after they transitioned from the seen world.

A medium is a gatekeeper between two worlds.  They deal with the messages that familiar spirits have given them charge to communicate.

Mediums are not strictly psychopomps, intermediaries between the living and dead, thought they often have deceased individuals speak through them.   They are primarily channelers.

Channeling is not uncommon.  It is simply using yourself as the conduit of energy.  One does this as they dance, writer’s often experience this when characters come alive in their minds and even athletes do this when they focus their energy on reaching the goal.

Being the conduit of energy is something that artist and non artist alike have experienced at some point along their journey.  This makes them at that point a medium.

One who takes on the title of medium is able to completely squash their ego to the point that another spirit is able to speak through them.

An unchecked and imbalanced ego fights for dominance at every possible moment and hinders one from being able to tap into the deeper aspects of their powers.

It hinders them from being in the flow of the spirit and you miss alot when you are not in the flow.