witch's brew vs salmagundi

witch's brew and salmagundi both are nouns.

Word	Noun	Adjective	Verb	Adverb
witch's brew	Yes	No	No	No
salmagundi	Yes	No	No	No

As nouns, salmagundi is a hypernym of witch's brew; that is, salmagundi is a word with a broader meaning than witch's brew:

Other hypernyms of witch's brew include assortment, miscellanea, miscellany, mixed bag, mixture, motley, potpourri, smorgasbord, variety.

witch's brew (noun)	salmagundi (noun)
a fearsome mixture	cooked meats and eggs and vegetables usually arranged in rows around the plate and dressed with a salad dressing
	a collection containing a variety of sorts of things