see photos attached.
first photo is critter nation. the bars are mostly horizontal with a few vertical cross bars. bar spacing is 1/2 inch on this cage. the top and bottom sections both have double doors, opening the front of the cage wide up.
second photo is a ferret nation. the bars are mostly vertical with a few horizontal cross bars. bar spacing is 1 inch on this cage. the top and bottom sections both have double doors, opening the front of the cage wide up.
i believe the dimensions of the two cages are slightly different but the size difference between the two is miniscule.