Hobart is made by Miller. Basically uses the same parts, however, they aren't the same in one major area. First of all, I have a Hobart 175. I like the welder, but there is one major thing I would change about my welder. There are only four power settings. Basically, you can only have a choice of 1-2-3-4. The Miller has an infinite power setting between 1-10. So, if you need a 4.5 setting, you can use it. The Hobart doesn't allow for adjusting between a 3 and 4 setting. Its either 3 or 4. Most would say that this isn't a huge issue, but I've welded with my buddy's Miller 210 and its a huge benefit IMHO. The Miller is only around $50 more for comparable units. I say that $50 is worth it.
I love my Hobart, but the Miller is a better unit.