atomic number 91 vs protactinium

atomic number 91 and protactinium both are nouns.

Word	Noun	Adjective	Verb	Adverb
atomic number 91	Yes	No	No	No
protactinium	Yes	No	No	No

As nouns, atomic number 91 and protactinium are synonyms defined as:

atomic number 91 and protactinium: a short-lived radioactive metallic element formed from uranium and disintegrating into actinium and then into lead

Other synonyms of atomic number 91 include Pa, protoactinium.

atomic number 91 (noun)	protactinium (noun)
a short-lived radioactive metallic element formed from uranium and disintegrating into actinium and then into lead	a short-lived radioactive metallic element formed from uranium and disintegrating into actinium and then into lead