How does the position of the gray and white matter differ in the spinal cord and the cerebral hemispheres?

Answer 1

Think of it this way. The gray matter is where signals start from, and white matter is the path the signals take. So in the cerebral hemispheres, the gray matter is on the outside, and the white matter is on the inside (signals have to travel from the outside, thru the brain to get to the spinal cord). In the spinal cord however, its the other way, the gray matter is on the inside, and the white matter is on the outside (here, the signals start in the inner part and travel outward to rest of the body)

Answer 2

In spinal cord the gray matter is surrounded by white matter, in brain, on the other hand, white matter is surrounded by gray matter.
Remember, the butterfly inside the spinal cord consist of gray matter.

Answer 3

You only find matter with no myelin sheath in the brain