Ferdinan De Sassure has proposed Langue and Parole long before Chomsky proposed his Competence and Performance system of linguistic knowledge? I know that they are different but how?
The main difference is probably that Chomsky's competence is a purely individual notion: it's the linguistic knowledge of a single speaker-hearer. Saussure's langue, by contrast, is not a property of any one individual but exists only at the level of society.