Though they are all synonyms to each other, there could be slight differences in both meaning and application. Intelligent - having intelligence Smart - having quick witted intelligence. Smart can also be used to describe a well dressed person, or when used as a verb - to describe a sharp, stinging pain coming from a wound, or when used as an adverb - to describe a quick and brisk manner, Clever - apart from intelligent and smart as its synonyms, it can also be used to describe someone who is crafty, skilled, talented, shrewd, gifted, etc.