farmland vs plowland

farmland and plowland both are nouns.

Word	Noun	Adjective	Verb	Adverb
farmland	Yes	No	No	No
plowland	Yes	No	No	No

As nouns, farmland and plowland are synonyms defined as:

farmland and plowland: arable land that is worked by plowing and sowing and raising crops

Other synonyms of farmland include cultivated land, ploughland, tillage, tilled land, tilth.

farmland (noun)	plowland (noun)
a rural area where farming is practiced	arable land that is worked by plowing and sowing and raising crops
arable land that is worked by plowing and sowing and raising crops