"There are all sorts of picture books. There is a place for them all."
- Charlotte Zolotow
in Making Picture Books: The Words
There is no hard and fast rule to distinguish a graphic novel from a picture book. However, there are several features that are often found in graphic novels:
Sometimes picture books also include these features so a book might fall into more than one category. Read more about the subtlties of graphic novels in this Horn Book article.