fallow vs cultivated land

fallow and cultivated land both are nouns.

Word	Noun	Adjective	Verb	Adverb
fallow	Yes	Yes	No	No
cultivated land	Yes	No	No	No

As nouns, cultivated land is a hypernym of fallow; that is, cultivated land is a word with a broader meaning than fallow:

fallow: cultivated land that is not seeded for one or more growing seasons
cultivated land: arable land that is worked by plowing and sowing and raising crops

Other hypernyms of fallow include farmland, ploughland, plowland, tillage, tilled land, tilth.

fallow (noun)	cultivated land (noun)
cultivated land that is not seeded for one or more growing seasons	arable land that is worked by plowing and sowing and raising crops

fallow (adjective)	cultivated land (adjective)
undeveloped but potentially useful
left unplowed and unseeded during a growing season