Substituting and using KA 'bread flour' instead of KA 'all purpose'?
I am an amature bread maker and I would like to know what would be the ramifications if "bread flour" was used instead of the "all purpose flour" in this baguette recipe. http://www.kingarthurflour.com/baking/documents/baguette-ciabatta.pdf 
How would the structure, texture, rise, and taste of the bread change if I were to use bread flour instead?
I also trying to wrap my mind around why KA makes a bread flour, but in most of their bread recipes they use all purpose flour. Can someone also assist me with this thought?