Whats The Difference Between Cydia And Rock Cydia Or Rcok For Jailbroken ITouch?.......................…

Cydia or Rcok for jailbroken iTouch?.......................… - whats the difference between cydia and rock

I have a 3G 8GB Jailbroken iTouch shock now, Ive been a choice between two packages, Cydia, and rock.

What should I choose (which is better)?

What is the difference between the two?

could and should choose two?

Thank you for your time