costoaxillary vein vs vena

costoaxillary vein and vena both are nouns.

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

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

costoaxillary vein: one of several veins connecting intercostal veins with the lateral thoracic vein or the thoracoepigastric vein
vena: a blood vessel that carries blood from the capillaries toward the heart

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

costoaxillary vein (noun)	vena (noun)
one of several veins connecting intercostal veins with the lateral thoracic vein or the thoracoepigastric vein	a blood vessel that carries blood from the capillaries toward the heart