parotid vein vs vena

parotid vein and vena both are nouns.

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

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

parotid vein: parotid branches of the facial vein; they drain part of the parotid gland and empty into the retromandibular vein
vena: a blood vessel that carries blood from the capillaries toward the heart

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

parotid vein (noun)	vena (noun)
parotid branches of the facial vein; they drain part of the parotid gland and empty into the retromandibular vein	a blood vessel that carries blood from the capillaries toward the heart