stylomastoid vein vs vena

stylomastoid vein and vena both are nouns.

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

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

stylomastoid vein: a vein that drains the tympanic cavity and empties into the retromandibular vein
vena: a blood vessel that carries blood from the capillaries toward the heart

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

stylomastoid vein (noun)	vena (noun)
a vein that drains the tympanic cavity and empties into the retromandibular vein	a blood vessel that carries blood from the capillaries toward the heart