Um, no. They're both owned by the same company, Illinois Iron Works I believe.
This was a helpful thread though: http://www.millerwelds.com/resources...-vs-miller-140
The main difference, besides the colors, seem to be the adjust-ability of the power. Maybe a few other parts are Black and Decker quality versus DeWalt commercial. Both have the new dual voltage which is cool. Miller maybe has an automatic setting that the Hobart doesn't.