In most cases the outdoor exhibits are far superior to any that are inside. The lack of natural substrate or even fresh air and genuine sunlight destroys indoor exhibits for me.
Good question. I believe that they are the same species, but simply too different groups. The colobus that are in with the Allen's swamp monkeys have an awesome habitat, while the colobus in the old primate house have an atrocious exhibit that is eventually going to be renovated.