grab bag vs miscellany

grab bag and miscellany both are nouns.

Word	Noun	Adjective	Verb	Adverb
grab bag	Yes	No	No	No
miscellany	Yes	No	No	No

As nouns, miscellany is a hypernym of grab bag; that is, miscellany is a word with a broader meaning than grab bag:

Other hypernyms of grab bag include assortment, miscellanea, mixed bag, mixture, motley, potpourri, salmagundi, smorgasbord, variety.

grab bag (noun)	miscellany (noun)
a container from which a person draws a wrapped item at random without knowing the contents	an anthology of short literary pieces and poems and ballads etc.
an assortment of miscellaneous items	a collection containing a variety of sorts of things