A lot of dual voltage welders have a lower output when running on 110v. Download the spec sheet and see what it says.
20a less max power means you cant weld as thick as you can with a 200a machine, may also meen the duty cycle is less (time before it overheats and you have to wait for it to cool down) but not always.
Again, download the specs for both machines and compare them.
As above, a lot less amps available on 110v. If you're thinking about site work most of the ones I have been on recently have 240v if only for the rediculous amount of Makita chargers that congregate around them.