Disclaimer, not an expert by any means and going off of old memory. There’s a loose square root correlation for laser strength to cutting depth, and which materials you can cut in the first place. So a stronger laser can cut deeper with fewer passes, and a weaker laser will require much longer to make the same kind of cuts.
You might say at 1.6W the laser cutter is really more of an engraver for easily burned materials (leather, paper, cardboard, SOME plastics), and at 40W it starts being able to pierce through those sorts of materials.