The answer is: Both biographies and autobiographies cover the important events in the subject’s life.
A biography and an autobiography differ most importantly in the nature of the author. An autobiography is written by the person who lived through the events recounted in the narration, whereas a biography is written by a third person who recounts the events in somebody else´s life. However this difference may impact the actual narration, it does not forsake its main purpose, which is to recount the main events in a subject´s life within an objective historical and social context that needs to cement the perspective adopted in the choosing of the events and their elaboration in the narrative.
