atomic number 89 vs Ac

atomic number 89 and Ac both are nouns.

Word	Noun	Adjective	Verb	Adverb
atomic number 89	Yes	No	No	No
Ac	Yes	No	No	No

As nouns, atomic number 89 and Ac are synonyms defined as:

atomic number 89 and Ac: a radioactive element of the actinide series; found in uranium ores

Other synonyms of atomic number 89 include actinium.

atomic number 89 (noun)	Ac (noun)
a radioactive element of the actinide series; found in uranium ores	a radioactive element of the actinide series; found in uranium ores