Mind is non physical and non material, it is thought. Thought is not located in space, and occupies a private universe of it own. E.g. yours mind belongs to you, his mind belongs to his. We can not tap into other people's mind.

Brain is a physical organ located in space. E.g the part of brain that controls the optics will process the signal arrives from the retina. Technically the entire processes of optical behavior could be studied in reductionism science.

This is what we called when physical world meets mental world. To study AI, scientists need to understand if matter acts on mind or mind acts on matter? Also, to study AI, need to understand determinism (algorithm based control) or free will (how could the machine make decision of it owns).

Let me branch out a bit. One question, how do you know your neighbour John has a mind? Is it because you have a mind and he behaves like you, by using deduction, you make a conclusion he has a mind too?

This deduction is actually an act of faith. Why, because you could never ever experience his consciousness, if you could, then that person is no longer him, he is you......So how could you conclude that he has a mind? It appears that everyone makes assumption that they have mind and also have faith to assume that others have mind too.

Now, how can we deduce that a machine (with AI capability) has a mind??

At the end of the day, sciences is just a prime mover for us to explain the universe, no matter how far and how well our sciences and technology advancement,  a lot of the big questions would still need to rely on philosophy and potentially metaphysics.

I think, therefore, I am - Rene Descartes