subclavian vein vs vena

subclavian vein and vena both are nouns.

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

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

subclavian vein: a continuation of the axillary vein; joins the internal jugular to form the brachiocephalic vein
vena: a blood vessel that carries blood from the capillaries toward the heart

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

subclavian vein (noun)	vena (noun)
a continuation of the axillary vein; joins the internal jugular to form the brachiocephalic vein	a blood vessel that carries blood from the capillaries toward the heart