Eu vs metallic element

Eu and metallic element both are nouns.

Word	Noun	Adjective	Verb	Adverb
Eu	Yes	No	No	No
metallic element	Yes	No	No	No

As nouns, metallic element is a hypernym of Eu; that is, metallic element is a word with a broader meaning than Eu:

Eu: a bivalent and trivalent metallic element of the rare earth group
metallic element: any of several chemical elements that are usually shiny solids that conduct heat or electricity and can be formed into sheets etc.

Other hypernyms of Eu include metal.

Eu (noun)	metallic element (noun)
a bivalent and trivalent metallic element of the rare earth group	any of several chemical elements that are usually shiny solids that conduct heat or electricity and can be formed into sheets etc.