You ask what the difference is between members of the French Academy and the Academy of Sciences? Haha, first of all, their numbers are different. The French Academy has 40 members, who serve for life. A position can only be filled after a member dies and a new one is elected by the current members. Because of this rule, many prominent figures have not been granted the title of an academician throughout their lives. For this reason, all members of the French Academy have a special title - the Immortal.
Secondly, members of the Academy of Sciences need only make a breakthrough in the study of Natural Philosophy to be elected. Most people who become members of the Academy of Sciences cannot be elected to the French Academy. However, those Natural Philosophers who are elected to the French Academy are invariably members of the Academy of Sciences.
