MarkB
Legend
Why does this distinction really matter, given it all looks like magic? Why is telekenisis with "mind powers" meaningfully non-magical in a world where a wizard also moves objects about without touching them? Isn't this all "Unexplained mysterious physics-breaking stuff that a few can do"?
If psionics is only just being introduced to a game-world, it can make a big difference in story terms, because even to wizards and scholars who know exactly how magic works, psionics will be unexplained physics-breaking stuff, and they have no idea how it's done.
Even in a world where it's well-established, it matters whether or not magic and psionics are the same or different - not just because of the anti-magic-field issue, but because that will affect how it's viewed by individuals, societies and religions, and how it interacts with the game-universe on a metaphysical level. That may never come into play in some campaigns, but it will impact others, and sometimes major plot points may hinge upon the difference.