assortment vs mixed bag

assortment and mixed bag both are nouns.

Word	Noun	Adjective	Verb	Adverb
assortment	Yes	No	No	No
mixed bag	Yes	No	No	No

As nouns, assortment and mixed bag are synonyms defined as:

assortment and mixed bag: a collection containing a variety of sorts of things

Other synonyms of assortment include miscellanea, miscellany, mixture, motley, potpourri, salmagundi, smorgasbord, variety.

assortment (noun)	mixed bag (noun)
the act of distributing things into classes or categories of the same type	a collection containing a variety of sorts of things
a collection containing a variety of sorts of things