The Ghost Writer (2010)
a) Blair went to Oxford, Lang to Cambridge.
b) Lang was an actor. Blair was in a rock band and did some comedy.
c) Blair qualified as a lawyer, and met his future wife when they worked for the same law firm. Lang seems to have met his wife through politics.
d) Cherie Blair has been a successful lawyer in her own right. Lang's wife seems not to have a job or career except as a politician's wife.
The differences might have been relevant had Blair sued for libel.