kilogram vs weight unit

kilogram and weight unit both are nouns.

Word	Noun	Adjective	Verb	Adverb
kilogram	Yes	No	No	No
weight unit	Yes	No	No	No

As nouns, weight unit is a hypernym of kilogram; that is, weight unit is a word with a broader meaning than kilogram:

kilogram: one thousand grams; the basic unit of mass adopted under the Systeme International d'Unites
weight unit: a decimal unit of weight based on the gram

Other hypernyms of kilogram include metric weight unit.

kilogram (noun)	weight unit (noun)
one thousand grams; the basic unit of mass adopted under the Systeme International d'Unites	a unit used to measure weight
	a decimal unit of weight based on the gram