Copics and Distress Markers blend differently. Copic markers blend well one over the other and come, as you know, in MANY different shades. So you can get a really nice gradiant look from light to dark just by layering.
Unlike Copics, Distress Markers are reactive with water and so their best blending is attained by using a water brush. Not only can it take one color and you can spread the color that you applied or you can help to colors to blend together that way.
Watch this video where Tim Holtz demonstrates how to do this.