Some people use the words interchangeably, you'll find cream puff recipes filled with whipped cream or ice cream and profiteroles filled with pastry cream. To me (and I'm bound to get some argument on this, I'm sure) this is sheer blasphemy. Cream puffs ought to be filled with pastry cream and topped with powdered sugar, while profiteroles are filled with ice cream and topped with warm ganache. The bases (choux pastry) are the same though!