For my book Midnight Playground: Where the Soul Plays, I offer this explanation to the ebook readers. I noticed the formatting difference when I looked at a copy on a friend's Nook. I don't know how to have it changed or if it can. So in light of that I thought I'd offer a little explanation to help in case you are confused.
The main character Simone is a writer (surprise!) and she has a blog called midnightplayground.com. Her blog posts are separated out by solid lines and have dates. These posts give you the reader an insight into what is going on in her mind during the story.
She also (which you find out in the book) wrote a book after Brian left her five years ago called Midnight Playground: Where the Soul Plays. There are three "chapters" from that book inside this story. In the print version, those chapters are separated by a different font and design. Unfortunately that didn't happen in the ebook. You know you are reading a chapter because they start with the title Midnight Playground: Where the Soul Plays and then give you the Chapter and the title of that Chapter (they are Counting Cars, Playing the Midnight Blues, and Two Thousand Steps). These 'chapters' give you insight on Simone's past.
I hope that helps and that I've not made it any more confusing.
Happy Reading, enjoy the Playground.