valve vs valvula

valve and valvula both are nouns.

Word	Noun	Adjective	Verb	Adverb
valve	Yes	No	No	No
valvula	Yes	No	No	No

As nouns, valvula is a hyponym of valve; that is, valvula is a word with a more specific, narrower meaning than valve:

valve: a structure in a hollow organ (like the heart) with a flap to insure one-way flow of fluid through it
valvula: a small valve

Other hyponyms of valve include cardiac valve, heart valve, valvelet, valvule, ileocecal valve.

valve (noun)	valvula (noun)
one of the paired hinged shells of certain molluscs and of brachiopods	a small valve
the entire one-piece shell of a snail and certain other molluscs
control consisting of a mechanical device for controlling the flow of a fluid
device in a brass wind instrument for varying the length of the air column to alter the pitch of a tone
a structure in a hollow organ (like the heart) with a flap to insure one-way flow of fluid through it