venae esophageae vs vena

venae esophageae and vena both are nouns.

Word	Noun	Adjective	Verb	Adverb
venae esophageae	Yes	No	No	No
vena	Yes	No	No	No

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

venae esophageae: small veins from the esophagus emptying into the brachiocephalic vein or the azygos veins
vena: a blood vessel that carries blood from the capillaries toward the heart

Other hypernyms of venae esophageae include vein, venous blood vessel.

venae esophageae (noun)	vena (noun)
small veins from the esophagus emptying into the brachiocephalic vein or the azygos veins	a blood vessel that carries blood from the capillaries toward the heart