fruit juice vs beverage

fruit juice and beverage both are nouns.

Word	Noun	Adjective	Verb	Adverb
fruit juice	Yes	No	No	No
beverage	Yes	No	No	No

As nouns, beverage is a hypernym of fruit juice; that is, beverage is a word with a broader meaning than fruit juice:

Other hypernyms of fruit juice include drink, drinkable, potable.

fruit juice (noun)	beverage (noun)
drink produced by squeezing or crushing fruit	any liquid suitable for drinking