I looked.

The main differences are

1. Magic Bookifier has more styles of builds you can use
2. Magic Bookifier allows you to write more for less. Their price is very high comparatively.
3. They have a WYSIWYG editor, which Magic Bookifier does not yet have.

I haven't used their software yet, but I definitely want to check it out. I mean, not for $6000 a year, but I will look into it more.