factor IV vs atomic number 20

factor IV and atomic number 20 both are nouns.

Word	Noun	Adjective	Verb	Adverb
factor IV	Yes	No	No	No
atomic number 20	Yes	No	No	No

As nouns, atomic number 20 is a hypernym of factor IV; that is, atomic number 20 is a word with a broader meaning than factor IV:

factor IV: ion of calcium; a factor in the clotting of blood
atomic number 20: a white metallic element that burns with a brilliant light; the fifth most abundant element in the earth's crust; an important component of most plants and animals

Other hypernyms of factor IV include Ca, calcium, clotting factor, coagulation factor.

factor IV (noun)	atomic number 20 (noun)
ion of calcium; a factor in the clotting of blood	a white metallic element that burns with a brilliant light; the fifth most abundant element in the earth's crust; an important component of most plants and animals