broth vs barley water

broth and barley water both are nouns.

Word	Noun	Adjective	Verb	Adverb
broth	Yes	No	No	No
barley water	Yes	No	No	No

As nouns, barley water is a hyponym of broth; that is, barley water is a word with a more specific, narrower meaning than broth:

Other hyponyms of broth include bouillon.

broth (noun)	barley water (noun)
a thin soup of meat or fish or vegetable stock	broth used to feed infants
liquid in which meat and vegetables are simmered; used as a basis for e.g. soups or sauces