The two laser has different wavelength, Fiber laser machine has Typical characteristics of 1064 nm wavelength range, and it’s able to process very wide range of materials from nonmetals to metals. However, it can’t process transparent objects like glass as the laser passes through such objects. And it creates contrast on plastics easily.
CO2 laser has Typical characteristics of 10600 nm wavelength range lasers, and it is a gas laser made with carbon dioxide gas. Such lasers are used for engraving/etching machines and laser markers. CO2 laser can’t be absorbed well by metals , also melting and burning always occur due to the long wavelength and transfer of heat.
Compared with the standard wavelength, processed plastics tend to be subjected to less colouration. Processing transparent objects such as glass and PET are possible.