cardinal vein vs vena

cardinal vein and vena both are nouns.

Word	Noun	Adjective	Verb	Adverb
cardinal vein	Yes	No	No	No
vena	Yes	No	No	No

As nouns, vena is a hypernym of cardinal vein; that is, vena is a word with a broader meaning than cardinal vein:

cardinal vein: any of the major venous channels in primitive adult vertebrates and in embryos of higher vertebrates
vena: a blood vessel that carries blood from the capillaries toward the heart

Other hypernyms of cardinal vein include vein, venous blood vessel.

cardinal vein (noun)	vena (noun)
any of the major venous channels in primitive adult vertebrates and in embryos of higher vertebrates	a blood vessel that carries blood from the capillaries toward the heart