Their brains are arranged differently having bigger parts of the brain, for example the occipital lobe can be bigger. That means that person can visually process information better or interprets images at a better quality. I believe it is a hereditary trait. Other parts of the brain like the primary motor cortex come out or extend a bit more than other parts of the brain.
it could be for any reason like some ppl are just born that way or it could mean they were droped as a baby or they could of hit it really hard xx