Question

What is the difference between atomic mass and atomic weight?

Answer 1

Atomic mass is just an agreed upon mass of the different elements

Atomic weight is a weighted average of the naturally occurring isotopes of the element

For example, if there was carbon 14 and carbon 15, but carbon 14 is found much more than carbon 15 is, then the average would be between 14 and 15, but skewed toward 14.