venae conjunctivales vs vena

venae conjunctivales and vena both are nouns.

Word	Noun	Adjective	Verb	Adverb
venae conjunctivales	Yes	No	No	No
vena	Yes	No	No	No

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

venae conjunctivales: veins draining the conjunctiva
vena: a blood vessel that carries blood from the capillaries toward the heart

Other hypernyms of venae conjunctivales include vein, venous blood vessel.

venae conjunctivales (noun)	vena (noun)
veins draining the conjunctiva	a blood vessel that carries blood from the capillaries toward the heart