The main difference between a memoir and a short story lies in their purpose and structure.
Purpose:
A memoir is an autobiographical account of real events in the author's life. It is typically written to reflect upon experiences and life lessons learned.
A short story is a work of fiction, meaning it is made up and not based on real events. It is written to provide readers with an entertaining story with unexpected twists and turns.
Structure:
A memoir tends to focus on a single event or main theme, while a short story is typically more complex and contains multiple elements. A memoir is generally written in chronological order, while a short story can contain several plot points, which do not necessarily have to be in linear order.
In summary, a memoir is intended to be a reflective piece about real events, whereas a short story is an imaginative story based on fiction.