While the terms are often used interchangeably, there's a slight difference:

* Atomic weight refers to the average mass of an element's atoms, taking into account the relative abundance of its isotopes. This is a weighted average, hence the term "weight."

* Atomic mass is the mass of a single atom of an element.

In practical applications, atomic masses are more precise and are generally preferred over atomic weights. However, the term "atomic weight" is still commonly used, especially in older texts and contexts where the distinction is not crucial.