the 4570 used HD 460, and 3570 use HD 2500.
hd 4600 is a much better than HD 2500.
From the processor itself, you will be looking at up to 5-15% performance increase going from ivy-bridge(i5-3570) to haswell (i5-4570)
HD 4600 should be able to play lower end games without a problem, i'm not to sure about HD 2500.
I would recommend going with the newest processor(i5-4570) as it's better.