Spec-wise, they are rated the same. The build quality on the top ones, and supposedly the middle ones you didn't picture with "4000w" on the dust cap was supposed to be better, being built here while the bottom ones are built in China. I've run all three styles with no noticeable differences in output, quality, etc. Someone told me the tinsel leads were woven in better on the MKI, and a few other minor differences, but nothing really worth hunting down one over the other, unless it's for aesthetic purposes.