barium vs metallic element

barium and metallic element both are nouns.

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

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

barium: a soft silvery metallic element of the alkali earth group; found in barite
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 barium include metal.

barium (noun)	metallic element (noun)
a soft silvery metallic element of the alkali earth group; found in barite	any of several chemical elements that are usually shiny solids that conduct heat or electricity and can be formed into sheets etc.