Differentiate between mass number and atomic mass of an element

Atomic mass is the weighted average mass of an atom of an element based on the relative natural abundance of that element's isotopes. The mass number is a count of the total number of protons and neutrons in an atom's nucleus.

The mass number is the product of number of protons and number of neutrons

The atomic number is the same as the mass number but just put amu next to the number