DR suppopsed to be: Krank fights with evil overlord. evil overlord swings his greatsword and hoping to chop Krank in two pieces. However the blade stops after cutting only half an inch into Krunk's body.
Or anything similar to: you get hit, but you just don't notice the strike (as much). Not so different than HP. But slightly different from AC (which stands for not getting hit at all).

Looking at a wound caused by a certain weapon:
-with high AC: there are no wounds.
-with lot HP: wounds are normal deep, but Boromir can find with even a dozen arrows in his heart.
-with DR: "You talking about these scratces? I fought with a cat."

(Altough personally I don't prefer the D&D solution about wounding and armors.)