atomic number 89 vs actinium

atomic number 89 and actinium both are nouns.

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

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

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

Other synonyms of atomic number 89 include Ac.

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