francium vs metallic element

francium and metallic element both are nouns.

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

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

francium: a radioactive element of the alkali-metal group discovered as a disintegration product of actinium
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 francium include metal.

francium (noun)	metallic element (noun)
a radioactive element of the alkali-metal group discovered as a disintegration product of actinium	any of several chemical elements that are usually shiny solids that conduct heat or electricity and can be formed into sheets etc.