Ukrainian convicts are probably going to get decent training first. It’s also likely they are going to go into some of the worst spots. Ukraine is outnumbered and they can’t afford to lose anyone, criminal or not, but it doesn’t mean they are going to have it easy.
Russia/Wagner hardly gave their convicts any training, maybe gave them guns and supplies and sent them to the front blind to find artillery locations. They were cannon fodder, pure and simple. Bakhmut was a slaughter.