cow pasture vs pasture land

cow pasture and pasture land both are nouns.

Word	Noun	Adjective	Verb	Adverb
cow pasture	Yes	No	No	No
pasture land	Yes	No	No	No

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

cow pasture: a pasture for cows
pasture land: a field covered with grass or herbage and suitable for grazing by livestock

Other hypernyms of cow pasture include grazing land, lea, ley, pasture, pastureland.

cow pasture (noun)	pasture land (noun)
a pasture for cows	a field covered with grass or herbage and suitable for grazing by livestock