nagami kumquat vs kumquat tree

nagami kumquat and kumquat tree both are nouns.

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

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

nagami kumquat: shrub bearing oval-fruited kumquats
kumquat tree: 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 cumquat, kumquat.

nagami kumquat (noun)	kumquat tree (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