PULL is where the content is being pulled from your server after the first visit. For instance lets say I visit your new post that was just published the content on that post will all be served by your server. However, lets say my friend goes to read that post the next day after I did. Then the content will be from the CDN as opposed to your web server.
PUSH is where all the content is instead uploaded onto the CDN as soon as you hit that publish button. Now you might be thinking that this is a smarter choice but it depends.
PULL is good if you are creating a highly dynamic website for instance I upload 5 games every 5 minutes. This way my server does not get overloaded by the constant uploading to my CDN.
PUSH is good for content that is not so dynamic for instance a simple blog post every week or so.
However, if you are using a powerful dedicated server then you should be albe to handle the load of using a PUSH method which might be more beneficial.
Hope that helps you decide!
