The difference between E series and C series lies in the former is the cost-effective model which pulse energy is not so powerful as the latter.
SFX-GS-MOPA-E Maximum Pulse Energy: 0.8mj@20W/30W; 1.5mj@60W/80W/100W
SFX-GS-MOPA-C Maximum Pulse Energy: 0.8mj@20W/30W; 2.0mj@60W/80W; 1.5mj@100W
Another Difference is the Machine Parts, for MOPA C We Use Import Parts, While MOPA E use China Famous Brand Parts.
Take Mopa 60W for instance, the max. pulse energy of E is 1.5mj whereas the C is 2mj. Their performance in most cases is similar, only in some extreme situation, the C is more outstanding