hepatic portal vein vs vena

hepatic portal vein and vena both are nouns.

Word	Noun	Adjective	Verb	Adverb
hepatic portal vein	Yes	No	No	No
vena	Yes	No	No	No

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

hepatic portal vein: a short vein that carries blood into the liver
vena: a blood vessel that carries blood from the capillaries toward the heart

Other hypernyms of hepatic portal vein include vein, venous blood vessel.

hepatic portal vein (noun)	vena (noun)
a short vein that carries blood into the liver	a blood vessel that carries blood from the capillaries toward the heart