When was "Differences" first conducted by a French composer and conductor? 
Différences (Berio):  It was written for the Domaine musical concerts in Paris and first performed in March 1959, conducted by Pierre Boulez. Pierre Boulez: Pierre Louis Joseph Boulez CBE (] ; 26 March 1925 – 5 January 2016) was a French composer, conductor, writer and organiser of institutions.
March 1959