venule vs vena

venule and vena both are nouns.

Word	Noun	Adjective	Verb	Adverb
venule	Yes	No	No	No
vena	Yes	No	No	No

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

venule: a minute vein continuous with a capillary
vena: a blood vessel that carries blood from the capillaries toward the heart

Other hypernyms of venule include vein, venous blood vessel.

venule (noun)	vena (noun)
a minute vein continuous with a capillary	a blood vessel that carries blood from the capillaries toward the heart