sherbet vs frozen dessert

sherbet and frozen dessert both are nouns.

Word	Noun	Adjective	Verb	Adverb
sherbet	Yes	No	No	No
frozen dessert	Yes	No	No	No

As nouns, frozen dessert is a hypernym of sherbet; that is, frozen dessert is a word with a broader meaning than sherbet:

sherbet: a frozen dessert made primarily of fruit juice and sugar, but also containing milk or egg-white or gelatin
frozen dessert: any of various desserts prepared by freezing

sherbet (noun)	frozen dessert (noun)
a frozen dessert made primarily of fruit juice and sugar, but also containing milk or egg-white or gelatin	any of various desserts prepared by freezing