The 686 is a K Frame the 586 is an L Frame. There are production differences that make the 586 L version a bit stouter such as a reinforced forcing cone, beefed up frame, full-length barrel underlug, and non-counterbored cylinder. Also, in the Talo special edition currently being sold, most if not all of the 686 MIM parts have been replaced by forged steel as you can tell from the trigger and hammer below. This latter point is also true of the current Talo .44 Magnum snubbie.
Generally speaking, in the extra-tuned 586 L-Comp versions, I have handled two of those and they have superior action to 686's, and that 586 feels closer to a Performance Center 627 of which I own two of the latter as well as a PC 629. No surprise there as the current S&W website brags that the 586 L-Comp's action is Performance Center tuned. (
Product: Model 586 L-Comp); and, that Talo 586 will run you North of $1,000 if you can find one new.
The current S&W Talo 586 is a 7-Shot with a 3" ported barrel moon clip ready with tritium front site on the S&W web page (pictured below).