We've come to understand that in the digital world the difference between one type of document and another is one of design style and frequency more than anything else. From the software's perspective it's all just content.
Design a document it with a lot of pretty pics, it becomes a magazine.
Design it with charts and pull quotes and you have a newsletter.
Design it with a few pics, but mostly text, you've got a newspaper.
Design it with all text and chapters, you've got a book.