As nouns the difference between idiot and simple
is that
idiot is (slang|derogatory) a proponent of intelligent design while
simple is (medicine) a preparation made from one plant, as opposed to something made from more than one plant.
As an adjective simple is
uncomplicated; taken by itself, with nothing added.
As a verb simple is
(transitive|intransitive|archaic) to gather simples, ie, medicinal herbs.