Since laser marking is a different technic than laser engraving, the results are different. The main difference is that laser marking adds a layer on top of the material whilst laser engraving removes a layer of the material.
During laser marking on a metal, the heat of the laser starts a chemical reaction between an added product and the metal. This chemical reaction leaves a permanant black marking on the surface of the material and enables us to add text and logos to stainless steel serial number tags for exemple.
While different materials such as wood and plastic are perfect candidates for laser engraving, some of them are not. This is especially true for metals because they are too hard for the laser to engrave them. This is when laser marking comes into play.