What is the difference b/w Push CDN & Pull CDN?

Pull CDN (Standard):

User asks for image.jpg.

CDN doesn't have it.

CDN asks your Server.

CDN saves it.

Next user gets it fast.

This needs Low maintenance.

Push CDN:

You upload image.jpg to the CDN before anyone asks for it.

This gives High control.

Use Case:

Netflix uses Push.

They pre-load movies to servers in your city at 4 AM so they are ready when you wake up