Autobiography vs Memoir

So, my mom was asking me (because I, the writer, know all of these things) what the difference was between an autobiography and a memoir. This was spurred because of Barbara Walters' new "memoir".

I told her I thought it was just a marketing ploy. Since memoir is selling so well now, calling this book a memoir would work a lot better than just saying it's an autobiography. It's probably not really a memoir.

But she needed a little more than that. So I said an autobiography was more straightforward information, which covers all, or a majority of, a person's life. Memoir, on the other hand, is more narrow. It will focus on an illness, or a significant theme or series of events in one's life. It is also creative nonfiction rather than just fiction. It should read more like a fictional tale.

This opened up a whole wild discussion about writing and who can/should be writing books, but that's not really important.

Mom wasn't really sure about my analysis, so I went on a search. Apparently:

"An autobiography focuses on the chronology of the writer's entire life while a memoir covers one specific aspect of the writer�s life. So, if I chose to write about my complete life up to this point, including growing up in Cincinnati, my time in New York, the few years I spent in Chicago and eventually landing at Writer's Digest, I'd write an autobiography. If wrote a book about the winter of my sophomore year in high school where I got my tongue stuck to an icy pole, I'd write a memoir."

So yeah. I don't know what Barbara Walters wrote or what Hillary Clinton wrote (mom's other question, hers is an autobio but written by someone else...) but it's something to think about. I don't know that I ever really thought about the difference, it just seemed very clear. Memoir is so much about the creative that it never came close to being similar. But to the normal American, can they understand the difference? Especially when I don't know that it's portrayed correctly and lines now blur?