knickknack vs bric-a-brac

knickknack and bric-a-brac both are nouns.

Word	Noun	Adjective	Verb	Adverb
knickknack	Yes	No	No	No
bric-a-brac	Yes	No	No	No

As nouns, knickknack and bric-a-brac are synonyms defined as:

Other synonyms of knickknack include knickknackery, nicknack, whatnot.

knickknack (noun)	bric-a-brac (noun)
miscellaneous curios	miscellaneous curios
a small inexpensive mass-produced article