I know the difference between the red and blue and there is at least two for sure that I can tell you about. The miller has steel wire feed rollers and that red thing has plastic...... can you say wear out fast. The other is that the miller weights more and if I am buying a machine that has a transformer in it I want a huge one it means it is more powerful. So there you go I have disproved another salesmen pitch, aka bs ........... and as always IMHO ..