tibial vein vs vena

tibial vein and vena both are nouns.

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

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

tibial vein: veins of the lower leg; empty into the popliteal vein
vena: a blood vessel that carries blood from the capillaries toward the heart

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

tibial vein (noun)	vena (noun)
veins of the lower leg; empty into the popliteal vein	a blood vessel that carries blood from the capillaries toward the heart