4570 is the newer generation of the 3570K, but the non-clockable version. the new gen hardware is often about 10% faster than the older gen. overclock the 3570 will get you to the stock 4570, but it will be much hotter than run the 3570 at stock. Heat and over voltage for hardware is always not recommended.
Plus, 4570 has a different cpu socket, thus the motherboard uses a older chipset which lacks features compared to the 4570's lga 1150.
Choosing a older cpu meaning using a older motherboard too.
I would go with the 4570 i5