I recently read biographies of Benjamin Franklin and Theodore Roosevelt concurrently: Walter Isaacson’s  Benjamin Franklin and Edmund Morris’s first volume The Rise of Theodore Roosevelt. Both were captivating men.
There are several similarities: both were scientific, both wrote prodigiously, both were very social people, both lived during and heavily influenced key moments in American history.
There are, of course, several differences as well. While Franklin eventually lived quite comfortably, his early life was not as financially secure as Roosevelt’s. Franklin was involved in the formation of a fledgling nation whereas Roosevelt presided over America’s emergence as a world power. Though both men were known for their humor, their personalities were very different. Franklin was light and laid back while Roosevelt was fiery and intense.
But the difference that strikes me most as I read their lives side by side is their personal character and their moral framework. Franklin was known for his simple, practical wisdom. His later political theory was focused on the common good. But, at least in Isaacson’s portrayal, there doesn’t seem to be much depth or firmness to these positions. There is a strong streak of pragmatism. And Franklin seems to have held to these commitments rather lightly and to have lived at the edge of propriety financially and relationally while offering much more stringent advice to others. Further, Isaacson depicts a self-centered and egotistical man more interested in the fawning acclaim of others than in fulfilling duties to his family.
Roosevelt, by contrast, was driven by a strong, unshakeable sense of right and wrong and was eager to defend it. He was abstemious with respect to alcohol, above reproach as concerns the opposite sex, and built his political reputation fighting corruption. There is no doubt that Roosevelt had a healthy ego. But his approach seems to have been more outward focused than that of Franklin.
Both men were products of their time and significant influencers of their times. But while Franklin claimed to be concerned about the common good, Roosevelt seemed to be genuinely concerned about his fellow man.