isp2605 has got it right...
Keep in mind the economy line up which also carries a three digit call sign (ie: 915, 910, 410, 908, 457)
Other than the names changing on the pistols, there have been numerous improvements on the S&W line of autos (at least as far as S&W is concerned. Many still wish nothing had been done to the original 39 and 59).
- Obvious cosmetic and asthetic alterations have been made.
- Most definitely improvements in the metals and fabrication of the 3rd Gen guns, Don't know if that would apply to the TSW line.
- The grips have been "improved" since. I and many believe the 1st and 2nd gen guns did not have good ergonomics, and many believe little has been done to improve the 3rd gen. The fact is that guns are like clothes and you simply need to find what fits. I bought my 4506 when I still owned my SIG P226. The SIG filled my hand very well, but when I finally grew into the 4506, I now find the grips on most S&W to be very comfortable. Different strokes for different folks....
- Steady imporovements in the function and reliability of the S&W's. Most who have experience with the S&W line of autos I have heard give the guns high marks in these areas. While the 39 series has a good reputation the life of the 59 series was spotty until the 3rd gen gun arrived on the scene.
These are just some minor details I can think of, and I am sure there are more. Bottom line is this... S&W has a very good handgun in the 3rd gen. line up, at any price, and have for some time. Quality and performance are up there with the others (SIG, Ruger, Beretta, et al.). At least this has been my experience with about a half a dozen S&W through my safe and several more loaners and rentals.
Good Shooting and God Bless!
