So basically, the Karman line is the theoretical highest point that an airplane can fly, or at least it was when it was calculated. If it were recalculated today it would be higher because of technological advancement. The definition used by the agencies that define it as the edge of space set an altitude near the originally calculated line. The functional difference between being above the line and below the line is that the keplar force will keep an object above the line from falling to Earth within 24 hours while drag will slow the object below the line enough for it to fall back to Earth within 24 hours. It's fine as a functional definition but I see no reason that it should be universally applied. In the scope of this discussion why should we consider something that will fall back to Earth in 25 hours not be on Earth but something that will fall back to Earth in 23 hours to be on Earth?