Physicalism is the proposition that all that exists does so within the limitations of the physical universe and that there are no other kinds of things other than the physical and things derived from the physical realm whether they be forms of energy, motion, or thought. Therefore, physicalism denies the supernatural. However, physicalists do recognize the reality of concepts since they consider them to be properties of the physical brain the way gravity would be a property of matter.
Everything in the world conforms to or is dependent on the physical realm. Therefore, concepts, for example, are dependent on the physical brain.
There is no real difference between materialism and physicalism since both posit that the universe is all that there is and that everything in it--gravity, light, thoughts, beauty, etc.,--are dependent upon the physical realm.
See also, What is physicalism?