Final answer:
A biography is a detailed account of a person's life written by someone else, while an autobiography is written by the person themselves. A memoir is a more focused narrative that centers on specific life experiences and themes from the author's perspective.
Step-by-step explanation:
A biography is a nonfiction story about a person's life, written by someone other than the subject. It provides a detailed account of another individual's life from birth to death or until a specific point in time, highlighting various aspects such as their relationships, career, and notable achievements.
An autobiography shares many similarities with biographies; however, the key difference is that an autobiography is written by the person whose life is being documented. This genre offers a first-person account of the author's life, shedding light on their perspective and internal experiences throughout their existence.
A memoir, while also a first-person narrative, differs from an autobiography in scope and purpose. Rather than covering an entire lifetime, a memoir typically focuses on a specific theme, time period, or collection of experiences that hold significant meaning for the author. Memoirs are often reflective and seek to share the emotional journey and personal insights of the writer with the reader.