Psionics vs. Magic
This essay is designed to illustrate the differences between psionics and magic. It also helps to illustrate the complaints some have about magic being able to take over psionics.
Psionic powers are related to control of the body and mind, as well as using the mind to force the will on the outside environment. AD&D created the psionic powers capable of rearranging matter and the body, Starcraft made the evil little mental moves, Rifts developed the use on the outside environment, and RPG Project developed combat psionics. Magic channels an ambient force through mental, magical and/or physical exertion to accomplish miracles. Let me a list a number of points:
1. Magic eventually learns mental psi combat type of powers (Mindshatter, Mental Blast) and rearranged matter, but a) way after most psionics and b) much worse. However, magic has a number of other things going for it.
2. Psionics have a definite real world basis. They are related to the human brain. However, they learn exorcism and supernatural combat much earlier. I'd say that psionics use their connection to the body as a way of anchoring their powers to the real world and thus becoming capable of fighting supernatural creatures safely and early on. They can make the fight on the psionic's home field and not the supernatural being's. Magic instead adopts the approach of fighting fire with fire, using the unreal and otherworldly to fight the unreal. But, the flip side of the coin comes from technology. Mental stunners, brain control units, and so on, will stop psionics dead.