They are not really comparable, Ma'anshan is about five times bigger than Visby (3 000 t and 600 t respectively). The Visby is not a true blue water corvette, the designation for it is actually (directly translated from swedish) coastal corvette.
I would say that Visby is harder to detect, but then Ma'anshan is a blue water ship. If they met in the Baltic Visby could come out on top, due to detecting the Ma'anshan first, if they met out on the ocean, Visby wouldn't feel at home at all. But this is speculations, a good skipper on one of the ships could be decisive. The key would be who would find the other one first, and simply because of size I suppose Visby has a smaller RCS.