to me buffing means to remove a product as in, "I am buffing wax residue." It seems alot of people think of buffing as using an old orbital or maybe a rotary with a large wool pad to remove scratches from cars.
When i say polishing i think of paint correction removing scratches and swirls and leaving the car with a nice finish, compound to polish or an all in 1 product like xmt 360. i suppose polishing could also mean something like meg color x, and remove oxidization.