facial vein vs vena

facial vein and vena both are nouns.

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

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

facial vein: any of several veins draining the face
vena: a blood vessel that carries blood from the capillaries toward the heart

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

facial vein (noun)	vena (noun)
any of several veins draining the face	a blood vessel that carries blood from the capillaries toward the heart