The 55# pizzeria flour is in bag that has two layers of paper, the exterior with the printing on it, and the interior brown paper. The pizzeria bag also has a blue plastic lining on the top of the bag. The small chef bag is a single layer of a different white paper.
I have noticed that the chef isn't capable of absorbing as much water. I would blame it on the packaging allowing the flour to absorb water out of the air more easily than the double blue bag.
Just a guess. other than the absorption issue, they seem exactly the same to me.