Holy crap, they're showing nine different versions. That's the most I've ever seen for a single AE shoe. Clearly they're going all-in.
I see several folks have responded to your original post. Yes, AE has one standard brown shell color which they (sometimes) refer to as either brown or dark brown - but it is the same color.
During the ongoing Trunk Sale, they have introduced 2 new "brown range" shell colors - a Natural shell (light brown) and a Deep Dark Brown, but these are just for a limited time only.
What's of particular note now is that, during the span of the Trunk Sale, you can order any AE dress shoe or boot in their standard brown (or burgundy or black) shell for no MTO fee ($125 savings!!). So for now, ALL AE dress shoes and boots are available in standard brown shell for no additional charge.
Just gorgeous. I sometimes find myself wishing for Allen Edmonds to make a balmoral boot in the same style though!