Jim, the two 1911s pictured above are both technically M1991A1's. They both have the same Colt stock number, #01991. What Colt did recently was add a stainless barrel and begin brush-finishing the flats, in addition to changing the slide rollmark to a more eye-pleasing one.
The rollmarks are added late in the manufacturing process, and if you'll look at a Colt you'll see they're actually applied after the slide and frame have been polished. At one time the polishing was done afterwards, but since around the time of the early Series 80 models Colt changed the order in which they did it. You can tell because the rollmarks have raised metal from when it was displaced during the stamping operation. IMO the markings would look better if the slides were polished afterwards, and the raised metal surface removed..