Eu vs atomic number 63

Eu and atomic number 63 both are nouns.

Word	Noun	Adjective	Verb	Adverb
Eu	Yes	No	No	No
atomic number 63	Yes	No	No	No

As nouns, Eu and atomic number 63 are synonyms defined as:

Eu and atomic number 63: a bivalent and trivalent metallic element of the rare earth group

Other synonyms of Eu include europium.

Eu (noun)	atomic number 63 (noun)
a bivalent and trivalent metallic element of the rare earth group	a bivalent and trivalent metallic element of the rare earth group