hepatic vein vs vena

hepatic vein and vena both are nouns.

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

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

hepatic vein: a vein that drains the liver; empties into the vena cava
vena: a blood vessel that carries blood from the capillaries toward the heart

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

hepatic vein (noun)	vena (noun)
a vein that drains the liver; empties into the vena cava	a blood vessel that carries blood from the capillaries toward the heart