This is what the new-production 1991A1 looks like:
Note the new, non-ugly markings (instead of "COLT 1991A1" in big letters), nicer blued finish, rosewood grips and long aluminum trigger. It doesn't say "1991A1" anywhere on the gun, but the model number is still 1991. If my experience is any indication, aside from looks the guns themselves are alot better, too.
And this is what the new-production Series 70 looks like:
Differences between the two? Most obviously, the S70 has different markings, a nicer, more polished blue finish, different sights & trigger, and no firing pin block safety. It also costs about $300 more than the 1991A1.