Because I can broadcast my thoughts into your head, the same way I can pick up thoughts you broadcast out. I can also do other things with it, like putting up mental blocks around memories or powers, deep diving into someone's mind, dreamwalking, astral travel, just about everything you could imagine a telepath doing.
The brain controls everything you perceive, right? So if I tell you're in, let's say, a manure-soaked farm but I tell your brain you're in your favorite bakery, complete with the sights, smells, and sounds of the place...well, in reality you're standing in a manure-soaked farm, but you won't perceive any of that. As far as every sense you have is concerned, you're in your favorite bakery.
That's just a term for somebody who has multiple mental abilities. It's also the type of energy we use. If two psychics are fighting, we say "psionic attack" instead of "mental attack". ...So basically, it's an ego thing.
You ever want a lift somewhere, I'm usually around.