atomic weight vs atomic mass

atomic weight and atomic mass both are nouns.

Word	Noun	Adjective	Verb	Adverb
atomic weight	Yes	No	No	No
atomic mass	Yes	No	No	No

As nouns, atomic weight and atomic mass are synonyms defined as:

atomic weight and atomic mass: (chemistry) the mass of an atom of a chemical element expressed in atomic mass units

Other synonyms of atomic weight include relative atomic mass.

atomic weight (noun)	atomic mass (noun)
(chemistry) the mass of an atom of a chemical element expressed in atomic mass units	(chemistry) the mass of an atom of a chemical element expressed in atomic mass units