sticker vs toughie

sticker and toughie both are nouns.

Word	Noun	Adjective	Verb	Adverb
sticker	Yes	No	No	No
toughie	Yes	No	No	No

As nouns, sticker and toughie are synonyms defined as:

sticker and toughie: a particularly difficult or baffling question or problem

Other synonyms of sticker include poser, stumper.

sticker (noun)	toughie (noun)
a short knife with a pointed blade used for piercing or stabbing	a particularly difficult or baffling question or problem
an adhesive label	an aggressive and violent young criminal
a particularly difficult or baffling question or problem
a small sharp-pointed tip resembling a spike on a stem or leaf