central veins of liver vs vena

central veins of liver and vena both are nouns.

Word	Noun	Adjective	Verb	Adverb
central veins of liver	Yes	No	No	No
vena	Yes	No	No	No

As nouns, vena is a hypernym of central veins of liver; that is, vena is a word with a broader meaning than central veins of liver:

central veins of liver: terminal branches of the hepatic veins that lie in the hepatic lobules and receive blood from the liver sinusoids
vena: a blood vessel that carries blood from the capillaries toward the heart

Other hypernyms of central veins of liver include vein, venous blood vessel.

central veins of liver (noun)	vena (noun)
terminal branches of the hepatic veins that lie in the hepatic lobules and receive blood from the liver sinusoids	a blood vessel that carries blood from the capillaries toward the heart