What is the performance difference between 2600k and 3770k?

On ppbm5 the 2600k shows up frequently. The 3770k does not. Why, if the 3770k is a better chip? If so, what makes it better?

There is a $10 difference between the 2700k and the 3770k at my local retailer. I'll definitely go the extra but i want to know for certain that i'll be gettig a chip as reliable as the 2600k.

Thanks