potpourri vs grab bag

potpourri and grab bag both are nouns.

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

As nouns, grab bag is a hyponym of potpourri; that is, grab bag is a word with a more specific, narrower meaning than potpourri:

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