Hansli covered the basic differences well. There is one more thing of importance depending on your intended use. The 686 models I've shot have an automatic safety that is a pure pain in the @$$, not to mention the thumb if you're shooting clay targets. While I distrust all safety's the automatic ON safety is at best a nightmare when shooting clays. There is now a Sporting 686 offered and I don't know if it has the auto safety or not, but if it does, you may want to steer clear of it and get the 682...just a thought.
