I am an avid reader, and noticed that books I checked out from the library lately seem to use "memoir" and "biography" interchangeably, although they are all shelved as "biographies". Is there an actual semantic difference between "memoir" and "biography"? Or is it just something that comes down to personal preference?
A memoir is a sub-genre of the autobiography. As Wikipedia writes:
The criteria for determining whether a work is a memoir include:
A biography, on the other hand, is a broader category. From Wikipedia:
Biographies tend to be about someone's entire life, although a memoir is still a type of biography. The library would shelve them together because of their shared overarching category.
Simply put, a memoir is usually written by the person whose life the writing describes, while a biography may be written by another person.