hectare vs area unit

hectare and area unit both are nouns.

Word	Noun	Adjective	Verb	Adverb
hectare	Yes	No	No	No
area unit	Yes	No	No	No

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

hectare: (abbreviated `ha') a unit of surface area equal to 100 ares (or 10,000 square meters)
area unit: a system of units used to measure areas

Other hypernyms of hectare include square measure.

hectare (noun)	area unit (noun)
(abbreviated `ha') a unit of surface area equal to 100 ares (or 10,000 square meters)	a system of units used to measure areas