ley vs cow pasture

ley and cow pasture both are nouns.

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

As nouns, cow pasture is a hyponym of ley; that is, cow pasture is a word with a more specific, narrower meaning than ley:

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

Other hyponyms of ley include common land, commons.

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