falls vs body of water

falls and body of water both are nouns.

Word	Noun	Adjective	Verb	Adverb
falls	Yes	No	No	No
body of water	Yes	No	No	No

As nouns, body of water is a hypernym of falls; that is, body of water is a word with a broader meaning than falls:

falls: a steep descent of the water of a river
body of water: the part of the earth's surface covered with water (such as a river or lake or ocean)

Other hypernyms of falls include water.

falls (noun)	body of water (noun)
a steep descent of the water of a river	the part of the earth's surface covered with water (such as a river or lake or ocean)
the petals or sepals of a flower that bend downward (especially the outer perianth of an iris)