calculus vs ptyalith

calculus and ptyalith both are nouns.

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

As nouns, ptyalith is a hyponym of calculus; that is, ptyalith 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
ptyalith: calculus in a salivary gland

calculus (noun)	ptyalith (noun)
the branch of mathematics that is concerned with limits and with the differentiation and integration of functions	calculus in a salivary gland
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