In my experience, RF lenses from 50mm and down tend to be smaller and have less distortion than their SLR counterparts. Part of the size difference is that most RF lenses are manual focus still; part of it is because of design. RF wides generally seem to have more vignetting to me as well.
As far as sharpness and contrast goes, I think that has less to do with the differences between RF and SLR design nowadays (if it ever did) and more with the resources a particular company decides to pout into a particularly design.
As far as sharpness and contrast goes, I think that has less to do with the differences between RF and SLR design nowadays (if it ever did) and more with the resources a particular company decides to pout into a particularly design.