The points in which the atomic mass and atomic number differentiate are given below - Atomic mass represents the number of both protons and neutrons present in the nucleus combined together, while the atomic number just provides the number of protons present in the nucleus of the given element.Atomic mass is associated with the average weight of each atom of an element, but atomic number just tells about the number of protons or electrons present in the atom.The letter “A” is used to represent the atomic mass of an atom, while the atomic number is denoted by the letter “Z” ( or “Zahl”).Different atoms of the element can have different numbers of the atomic mass (due to the isotopes), but they will always have the same value for the atomic number.