Some of those are not S&W factory models, but may be modified by distributors or tacked on by people trying to get $100 bucks more than retail for the same gun. Window dressing that has no collector's value and will not significantly change resale (other than maybe reducing it) - similar to putting 20" wheels on a Chevy sedan (aka "bling"). Search "Talo" for a few (mostly negative) posts on that resale group.
*cracks open the Standard Catalog*
The current S&W nomenclature for the 686:
"Distinguished Combat Magnum" is the name S&W gave the 686 - all 686's are DCMs.
SSR, "Stock Service Revolver," is a model with a special barrel (angled underlength lug), grip, and tuned springs.
"Plus" refers to a 686 with a 7-shot cylinder.
There was a "deluxe" model I guess, the 686-5 DX, but it was only sold in 2000 through the S&W company store.
Unfluted cylinders were available from the factory for a brief time under the name "Euro-Hunter"
Other official model names included: Classic Hunter, Competitor, Action Revolver, CS-1 (made for US Customs Service), Powerport, Mountain Gun, Target Champion, Challenger, Carry Comp, and Super Target.