popliteal vein vs vena

popliteal vein and vena both are nouns.

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

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

popliteal vein: a vein arising in the knee and ascending to become the femoral vein
vena: a blood vessel that carries blood from the capillaries toward the heart

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

popliteal vein (noun)	vena (noun)
a vein arising in the knee and ascending to become the femoral vein	a blood vessel that carries blood from the capillaries toward the heart