I read a little further and your right. I was going with the spec sheet at the bottom of the page. The duty cycle for the pro mig and the 175HD is broke down for 208V and 230V and the 175T is not. Why? I don't know. Those machines look just like the little 120 volt machine I've used to do light repair work out in the field with. I guess I just had a brain fart.
My guess would be, there's a difference in transformer configuration between the two. But the fact that they weigh the same shoots that idea down too. It's probably boils down to a marketing ploy so they can offer a wider range of products without changing anything but the catalog ID and the price.