Is it Middle Grade or Chapter Book?

You've finished that first draft of your middle grade novel. But now taking a long look, maybe not. Maybe it is a Chapter book. Or is it? 
How can you tell? Now it's not as clear as you first thought in your rapid fire, getting it all out on paper and spouting out to everyone, "I'm working on a middle grade story."
Going back to read or reread all the books that seem the slightest bit similar sometimes helps. And sometimes doesn't -
I found a blog by Emma Walton Hamilton with a clear way to compare.
She uses clues about: 
Audience
Age of Protagonist
Length
Illustration
Content
Yes, there are always exceptions!
I'm still researching every chapter and middle grade book I can get my hands on, but each morsel of information helps me on my journey.