There is supposedly no MIM used in the Fort Smith version. In the Smith version i think MIM was used. The Fort Smith slide's are made in Germany (so they must be of superior quality! Lol) The Smith were all US made I believe.
Others will have to jump in with details beyond that.
From what I've seen, the Fort Smith PPK/S is superior to my S&W PPK/S.
The fit/finish is better, especially on the slide. My S&W has "the fangs" going on at the front of the muzzle with sharp, pointed edges, whereas the Fort Smith models are properly countered, rounded off at the muzzle.
Also, the hammer and trigger on the Fort Smith PPK/S is stainless steel whereas they are MiM on my S&W with visible seems down the middle.