gaffe vs boo-boo

gaffe and boo-boo both are nouns.

Word	Noun	Adjective	Verb	Adverb
gaffe	Yes	No	No	No
boo-boo	Yes	No	No	No

As nouns, boo-boo is a hypernym of gaffe; that is, boo-boo is a word with a broader meaning than gaffe:

Other hypernyms of gaffe include bloomer, blooper, blunder, boner, botch, bungle, flub, foul-up, fuckup, pratfall.

gaffe (noun)	boo-boo (noun)
a socially awkward or tactless act	an embarrassing mistake