grab bag vs potpourri

grab bag and potpourri both are nouns.

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

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

grab bag (noun)	potpourri (noun)
a container from which a person draws a wrapped item at random without knowing the contents	a jar of mixed flower petals and spices used as perfume
an assortment of miscellaneous items	a musical composition consisting of a series of songs or other musical pieces from various sources
	a collection containing a variety of sorts of things