calculus vs urolith

calculus and urolith both are nouns.

Word	Noun	Adjective	Verb	Adverb
calculus	Yes	No	No	No
urolith	Yes	No	No	No

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

calculus: a hard lump produced by the concretion of mineral salts; found in hollow organs or ducts of the body
urolith: a urinary stone

calculus (noun)	urolith (noun)
the branch of mathematics that is concerned with limits and with the differentiation and integration of functions	a urinary stone
a hard lump produced by the concretion of mineral salts; found in hollow organs or ducts of the body
an incrustation that forms on the teeth and gums