citrus vs calamondin

citrus and calamondin both are nouns.

Word	Noun	Adjective	Verb	Adverb
citrus	Yes	No	No	No
calamondin	Yes	No	No	No

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

citrus: any of numerous fruits of the genus Citrus having thick rind and juicy pulp; grown in warm regions
calamondin: a fruit of the calamondin tree.

citrus (noun)	calamondin (noun)
any of numerous fruits of the genus Citrus having thick rind and juicy pulp; grown in warm regions	a fruit of the calamondin tree.
any of numerous tropical usually thorny evergreen trees of the genus Citrus having leathery evergreen leaves and widely cultivated for their juicy edible fruits having leathery aromatic rinds