esophageal veins vs vena

esophageal veins and vena both are nouns.

Word	Noun	Adjective	Verb	Adverb
esophageal veins	Yes	No	No	No
vena	Yes	No	No	No

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

esophageal veins: 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 esophageal veins include vein, venous blood vessel.

esophageal veins (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