With controlled crying, I believe they recommend you keep on extending the time that you are out of the room. So you let them cry for a minute, then 2 mins, then 5, then 10 then 20 etc. Some people recommend that when you go to check on them, you don't let them see you.
With WIWO, you listen to your little one's cries, and decide if he is saying 'I need you' (or if he is trying to settle himself, or if he is just shouting). If he needs you, you don't wait, you go straight back in, and keep going back in as often and as many times as he needs you. That's a big difference from CC.