The biggest difference you will find between the newer Craftsman Adjustables and Crescent Adjustables arethe following:
Craftsman - thinner cross section overall, high carbon tool steel, jaw capacity still traditional (not as wide), thinner jaws, plating is different material (cobalt/nickle), plating is rougher to the touch a slight bit yellow in appearnce but more durable, generally tighter moveable jaws.
Crescent - made from their proprietary Alloy tool steel, a bit larger jaw capacity, bulkier with thicker cross section overall, looser moveable jaws. Chrome plating is whiter and smoother but the plating seems less durable.
Overall they are both pretty durable and high quality tools. I would place the newer Craftsmans as higher in quality overall thought. I personally don't like the newer plating or the bulkyness of the newer Crescent brand ones.
The older, pre-Cooper, Crescent adjustables were very good quality tools. I like the old versions much better than their newer offerings.
The USA made Craftsmans have always been a real high quality adjustable wrench. They have been made for sears by a few different companies over the years i.e. Utica, JH Williams, JP Danielson, and within the last 30 years by Western Forge. Interestingly enough Western Forge makes adjustables for many professional grade tool brands including newer S-K, Wright, Rigid, and a few others. In some cases I'm told they supply the exact same quality to most brands with only the roll marking being different and in some cases the styling being different. As in Rigid, they simply make a different style. They can make a special design upon customers request, but in general the steel, durability, heat treating, plating, and function are generally the same quality for all lines. You're just not paying as much for the Craftsman brand.