i5-4570 vs i5-4570s

[hp32sII]

I was wondering what is the technical difference between a standard cpu (like i5-4570) and the lower power s version (like the i5-4570s). Some people say you can make a i5-4570 behave exactly the same as a i5-4570s with the bios (but how do you do that ?) but then I don't understand why Intel is selling a i5-4570s. I know the tdp is different, but does that mean that a i5-4570s with a good cooler will perform (almost) like a i5-4570 with a standard cooler ? When I compare performance (based on cpubenchmark.net), then I see that a i5-4440s performs 6% less than a i5-4440, but a i5-4570s only 3% less then a i5-4570 : why is the performance difference not the same ? When I looked into these s versions, I was surprised that a 20% lower tdp only results in about 5% performance loss. Who knows more about these s versions ?