oval kumquat vs cumquat

oval kumquat and cumquat both are nouns.

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

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

oval 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 oval kumquat include kumquat, kumquat tree.

oval 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