CCV and PCV

What is the difference between Closed Crankshaft Ventilation (on Jeep
Grand Cherokees 4.0L) and Positive Crankshaft Ventilation (On 4.7L)?
Is CCV simply a vacuum based system sucking out Crankshaft gases,
while PCV has a valve to ensure no reverse vacuums due to backfires?
What are the pros and cons of both?

If these questions are not meant for this groups, please suggest where
I can ask such questions. I am a Jeep Grand Cherokee 2004 limited 4.0L
owner learning the engine internals - just for kicks and maybe to do
self-maintenance.

Thank you.