How do autobiographies differ from biographies?

In the context of nonfictional prose, the primary distinction between a biography and an autobiography lies in the identity of the narrator and the nature of the perspective.

• Biography: A biography is a literary account of an individual's life written by another person. The author draws upon various forms of evidence—including written, oral, and pictorial materials, as well as memory—to recreate the subject's life from a historical or personal perspective.1
• Autobiography: An autobiography is the biography of oneself, narrated by the subject. While a biographer relies on external research, an autobiographer possesses unique, private information about their own thoughts and actions. However, autobiographies are inherently shaped by the author's recollection, which is subject to conscious and unconscious omissions and distortions.23

Because memory is plastic and autobiographers often write to justify or reflect upon their own deeds, these works are sometimes described as "a sort of life" rather than an objective historical record. While both genres are forms of nonfictional prose, they offer different types of "biographical truth" based on whether the life is viewed from the outside or experienced from within.321