For the most part you only see three types of laser cutters on the market CO2 laser cutters, YAG laser cutters, and fiber laser cutters. These machines can often look very similar on the outside but there is always one way to tell. If you look in the compartment where the laser comes from and see a glass tube it is a CO2 laser cutter or engraver. If you open that compartment and see a metal box it is most likely a fiber laser it could also be a YAG. If your laser has no openable compartments and just has a diode it is most likely a YAG laser but could also be a fiber laser.