How do atomic mass and atomic weight differ?
Atomic mass and atomic weight mean the same thing, but atomic mass is the technically correct term.
Mass is the amount of matter in an object. It is usually measured in kilograms or grams. An object has the same amount of mass wherever it is located.
Weight is the force exerted on an object due to the acceleration of gravity. It is usually measured in newtons. The acceleration due to gravity varies from place to place, so weight varies as well.
Thus, atomic weight is an incorrect usage of the term, because the mass of an atom is constant.