How do people distinguish between “actually seeing it” and a visualization? I’ve heard it being used to memorize the digits of pi, so it’s clearly extraordinar

How do people distinguish between “actually seeing it” and a visualization? I’ve heard it being used to memorize the digits of pi, so it’s clearly extraordinary, but it’s difficult to see what is a normal reaction to music in the first place. I can’t imagine “just” perceiving the music at all.