nagami kumquat vs cumquat

nagami kumquat and cumquat both are nouns.

Word	Noun	Adjective	Verb	Adverb
nagami kumquat	Yes	No	No	No
cumquat	Yes	No	No	No

As nouns, cumquat is a hypernym of nagami kumquat; that is, cumquat is a word with a broader meaning than nagami kumquat:

nagami kumquat: shrub bearing oval-fruited kumquats
cumquat: any of several trees or shrubs of the genus Fortunella bearing small orange-colored edible fruits with thick sweet-flavored skin and sour pulp

Other hypernyms of nagami kumquat include kumquat, kumquat tree.

nagami kumquat (noun)	cumquat (noun)
shrub bearing oval-fruited kumquats	any of several trees or shrubs of the genus Fortunella bearing small orange-colored edible fruits with thick sweet-flavored skin and sour pulp