I think Jake is correct. I believe Miller own Esab... Personally I use and like Miller. Mine is an older unit that works great... I believe it is the Miller 251 model. I have run many large spools of wire through it and it works great every time!!! I have NEVER run into thermal limits or shutdown with it. Duty cycle is a VERY important spec for welders and I believe on my 251 it was rated at 80% duty cycle at full output meaning it would be capable of operating at its highest voltage and current settings for 80% of the time without thermal shutoff. Smaller units may only have 40% or even 10-20% duty cycle so be aware of the ratings and specs of machines you are considering.
If the Esab model is a dual MIG/TIG as mentioned above it is more versatile, but at what cost??? Is it less capable at either, are there sacrifices somewhere to do both???