I’ll take a stab at trying to explain it. It’s kind of like if you were to put your TV in front of a window in your home. Let’s say that you decided to watch a nature cartoon about sharks and elephants being friends. Your TV is your imagination and what you see out the window is what your eyes are seeing.

You see both the window and the TV at the same time but what you see out of the window is more “real.” What you see on the TV is also real but it’s real (and not real) in it’s own way. It’s real because you are ACTUALLY seeing sharks and elephants interacting on the screen. But it doesn’t feel AS real because one, it’s not happening in real time. It’s prerecorded. And two, because there will never be a situation where sharks and elephants are at the same place at the same time.

The prerecorded version is what it feels like to recall images from the past. And the odd completely made up situation of elephants and sharks being friends is what it’s like to make something up from scratch in your mind.