exhaust system pcv?

I want to know (I really do, not being sarcastic) why I'll see a high 11 second car have his pcv in the exhaust, and I'll see a low 10 second car run his off the valve cover?
I'd really like to know that trick and how you answer everybody's post all in one post? So for now I'll just have to answer individually.
I'm a little confused on this question straighten me out please? I would be using the vacuum from the exhaust to pcv through the valve cover?I know you weren't being sarcastic but I'm having trouble and it's probably just me understanding the question?