tilled land vs plowland

tilled land and plowland both are nouns.

Word	Noun	Adjective	Verb	Adverb
tilled land	Yes	No	No	No
plowland	Yes	No	No	No

As nouns, tilled land and plowland are synonyms defined as:

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

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

tilled land (noun)	plowland (noun)
arable land that is worked by plowing and sowing and raising crops	arable land that is worked by plowing and sowing and raising crops