californium vs metallic element

californium and metallic element both are nouns.

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

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

californium: a radioactive transuranic element; discovered by bombarding curium with alpha particles
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 californium include metal.

californium (noun)	metallic element (noun)
a radioactive transuranic element; discovered by bombarding curium with alpha particles	any of several chemical elements that are usually shiny solids that conduct heat or electricity and can be formed into sheets etc.