vena bulbi penis vs vena

vena bulbi penis and vena both are nouns.

Word	Noun	Adjective	Verb	Adverb
vena bulbi penis	Yes	No	No	No
vena	Yes	No	No	No

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

vena bulbi penis: vein of the head of the penis; tributary of the internal pudendal vein that drains the perineum
vena: a blood vessel that carries blood from the capillaries toward the heart

Other hypernyms of vena bulbi penis include vein, venous blood vessel.

vena bulbi penis (noun)	vena (noun)
vein of the head of the penis; tributary of the internal pudendal vein that drains the perineum	a blood vessel that carries blood from the capillaries toward the heart