What is the true difference between "psionics" and "magic"?
That is part of the discussion/ issue.
I see them as two very distinct things.
Psionics:
Cannot be dispelled, counterspelled, or subject to antimagic shell, etc.
Should be random to begin, but cultivated later on through training and experience.
Should be limited in scope, but significant in power by the end.
Should allow multiple effects (aka "stacking" concentration") at once.
Should be draining to the psion in a
fundamental way (hit points would be best).
Should be capable of doing things magic (barring perhaps
wish) can't. (
I'll add there should be MANY things magic can do that psionics can't, as well!!!)
Psions develop everything internally. But that makes their powers weak by comparison at first in some ways, but also as long as they have the "mental fortitude" to continue using their power, they can do so. They don't "run out of slots" or anything, except perhaps if you incorporate the draining I mention above. However, once they hit a limit, it should be harsh in my opinion. Their mind and/or body was pushed too hard and now they have to suffer the consequences.
Aren't there equal differences in those things between wizards and druids and necromancers and clerics? Why are psions special here?
Certain things I think should be involatile (?) when it comes to the magic of other classes. Wildshape should not be subject to antimagic shell, etc. for instance. Many channel divinities would also gain this benefit.
But fundamentally D&D has established that these classes all use magic (aka the Weave in FR, etc.) and "cast spells" to focus that magic. They draw from an external source, even if they channel that source internally (such as the sorcerer).
One could allow all forms of "magic" to be different, if one wanted. WotC doesn't, so the 5E doesn't. But it is the main reason I don't like Psion as "just another spellcaster". I like something more akin to Invocations or "powers" for psions, not spells, and those powers derived internally would be different from magic granted by an outside source.
That is how I differentiate them, at any rate.