smart as a whip vs brainy

smart as a whip and brainy both are adjectives.

Word	Noun	Adjective	Verb	Adverb
smart as a whip	No	Yes	No	No
brainy	No	Yes	No	No

As adjectives, smart as a whip and brainy are synonyms defined as:

smart as a whip and brainy: having or marked by unusual and impressive intelligence

Other synonyms of smart as a whip include brilliant.

smart as a whip (adjective)	brainy (adjective)
having or marked by unusual and impressive intelligence	having or marked by unusual and impressive intelligence