They are both counter punchers, but that is where the similarities end. Chuck used his wrestling base to stay on his feet and used his strong chin to walk though punches and land his overhand right. Now that he lost his chin and reflexes, he is easier to beat.
Machida, effectively uses his footwork to avoid getting hit, put in the clinch or taken down and impeccable timing to land solid strikes with fists, feet and knees. His chin has not yet been tested.