sealey just re badge their products like my air compressor is a fiac but badged a sealey.
migtymig are made by ERP
where as the super mig are made by telwin also weldabilty use the telwin welders but re badge them as weldabilty.
the supermig would be made by a better company also they are more versatile like they have low amps for body work and high amps for thicker stuff. wheras the mighty mig is kinda stuck in the middle and not much good for thin stuff