gardening vs agriculture

gardening and agriculture both are nouns.

Word	Noun	Adjective	Verb	Adverb
gardening	Yes	No	No	No
agriculture	Yes	No	No	No

As nouns, agriculture is a hypernym of gardening; that is, agriculture is a word with a broader meaning than gardening:

Other hypernyms of gardening include farming, husbandry.

gardening (noun)	agriculture (noun)
the cultivation of plants	the practice of cultivating the land or raising stock
	a large-scale farming enterprise
	the class of people engaged in growing food