Why purchase both?
The print version of the book is beautifully designed and filled with high-quality photographs, graphics, and full-page illustrations by Matt Kish (everypageofmobydick.blogspot.com). The foundation of my work is the creation of well-made objects. Some of this quality has necessarily been sacrificed to create files that can be easily downloaded and printed. However, owning digital copies of the patterns allows you to print out a working copy that you can carry with you and mark up while you knit without harming your book.