Fiber laser machines use a technology called Q-Switched laser resonator. The pulse width is fixed.
On the other hand, the Master Oscillator Power Amplifier known as MOPA works differently. By choosing different pulse width, MOPA laser is able to mark some colors on stainless steel, black color on aluminum & anodized aluminum.
Both machines can do similar jobs, however, if you are looking for a better finish in plastic materials and have the possibility of engraving different colors in stainless steel, or titanium, you can think about the solution that the MOPA laser can offer. On the other hand, if you are only looking to burn metals at high speed and do not need to engrave colors on metals; you can choose the standard fiber laser.
These machines may look the same. However, they are different not only in the effect of work and laser resonator, but also the price.