Why do people with ALS have all of their mental functions and senses intact while with people with Alzheimer’s don’t?

In Alzheimer's disease, as neurons are injured and die throughout the brain, and your brain regions begin to shrink, With ALS  motor neurons in your brain and spinal cord break down and die. When this happens, your brain can't send messages to your muscles anymore.

Explanation

ALS is pretty much only motor skills while Alzheimer's is NOT