Magicians are people who discover an odd quirk about the human body or brain or some unknown facet of science, then they figure out a way to trick people by hiding or misdirecting the truth and presenting it as “magic.” But… magicians are at least honest in admitting they are tricking you.
Psychics essentially do the same thing as magicians (discover some information or way to use psychology to read people or convince them of something), except they then use that information to exploit people by making them think it's real, rather than a trick like the magician.
The difference between magicians and psychics is evident by the fact that magicians such as Houdini and the Great Randy often debunk the claims of so-called “psychics” by proving how they did their tricks. Both magicians and psychics use similar cognitive tricks to make money off of people, but magicians are honest about the fact they are tricking you while the psychic never admits to lying.