accessory cephalic vein vs vena

accessory cephalic vein and vena both are nouns.

Word	Noun	Adjective	Verb	Adverb
accessory cephalic vein	Yes	No	No	No
vena	Yes	No	No	No

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

accessory cephalic vein: a vein that passes along the radial edge of the forearm and joins the cephalic vein near the elbow
vena: a blood vessel that carries blood from the capillaries toward the heart

Other hypernyms of accessory cephalic vein include vein, venous blood vessel.

accessory cephalic vein (noun)	vena (noun)
a vein that passes along the radial edge of the forearm and joins the cephalic vein near the elbow	a blood vessel that carries blood from the capillaries toward the heart