They are the same architecture so it theoretically has no difference. The i7 is a quad with psuedo core lite but its really only a quad core, the i5 is a pure quad, in overclocking ironically i5's generally overclock better. That or you can get non counter chips with much higher binned multi's, but it costs ya.
I have a hard time believing that anybody is running ivy bridge @5.0GHZ 24-7 stable unless they are using a rasa kit or better i would need to see proof to believe it anyway theoretically has no difference between those two chips other than what sarinaide mentioned.
even at 4.6ghz never mind 5ghz thats going to get hot
as ivy runs much hotter than sandy when overclocking heavily
Yeah i can hit 5.2GHZ 1.45V stable on my i5-2500k granted my temps are 87C so i don't keep it that way for longer than a benchmark run but on my i5-3570k if i go any higher than 4.7GHZ i would fry my chip in no time