They both agreed Germany and Japan should not be punished harshly as Germany was after World War I. They wanted peace and the creation of a world organization to prevent another war.
They differed in their approach and personality. FDR was a charmer and had gained the trust of Churchill (GB) and Stalin (USSR). Truman distrusted Stalin and vice versa. Truman was also willing to use the atomic bomb on Japan where FDR had not because he believed it was too harsh of a weapon.
