relative atomic mass vs atomic mass

relative atomic mass and atomic mass both are nouns.

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

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

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

Other synonyms of relative atomic mass include atomic weight.

relative atomic mass (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