Which part or characteristic of the nervous system is the most different when comparing humans with other animals?

The Cerebrum

Explanation:

The Cerebrum is that part of brain which is largest in size. The major function of cerebrum is to carry out voluntary functions and process information collected from the sense organs. Human are able perform intellectual activities such as logical thinking, reasoning, planning and decision making, humor, etc is due to more advanced cerebrum. Cerebrum has four different lobes where each lobe performs their special functions.