carbon group element vs Pb

carbon group element and Pb both are nouns.

Word	Noun	Adjective	Verb	Adverb
carbon group element	Yes	No	No	No
Pb	Yes	No	No	No

As nouns, Pb is a hyponym of carbon group element; that is, Pb is a word with a more specific, narrower meaning than carbon group element:

carbon group element: any chemical element that belongs to the carbon group.
Pb: a soft heavy toxic malleable metallic element; bluish white when freshly cut but tarnishes readily to dull grey

Other hyponyms of carbon group element include atomic number 82, lead, atomic number 50, Sn, tin, Fl, flerovium.

carbon group element (noun)	Pb (noun)
any chemical element that belongs to the carbon group.	a unit of information equal to 1000 terabits or 10^15 bits
	a soft heavy toxic malleable metallic element; bluish white when freshly cut but tarnishes readily to dull grey