Here in Canada we can get sweetened condensed milk OR evaporated milk. BOTH products have had 60% of the water removed BUT then the condensed milk has sugar added and the result is a rich & thick product that is 40 - 45 % sugar (ie VERY sweet!) and therefore pretty thick. There is nothing labelled "unsweetened" condensed milk here because essentially that is what evaporated milk is. Sugar is NOT added to evaporated milk but it is still thicker/richer than regular milk due to the water loss. Where I live, I can choose between regular and low fat evaporated milk. Apparently a skim version is made but I've never seen that choice on my small town grocery shelves. Brands I often see are Eagle Brand for the sweetened condensed and Carnation for the evaporated.
Based on the key properties of each of these products, I would assume that your "sweetened" and unsweetened" versions would correspond to these products.