Your content can only be in one of three states at any give time. If it is saved as a Draft then it is something that you are still working on, half completed paragraphs, needs images, and so on.
If it is in the queue that means that it is completed, however, it needs to be published by someone with the permissions to do so. Something in the queue will not be able to go out to subscribers in an automated newsletter. Content in the queue can come from authors within your organization or from your moderated content sources (RSS/XML feeds).
Once you approve a piece from the queue it will go to your Approved page. Once here it will start going out in individual newsletters based upon its chances of being opened by each subscriber. From the Approved page you still have the ability to edit posts and make any necessary changes on the fly.
The Content Archive and the Approved page mirror one another, the Content Archive being the public facing version that your subscribers can access through the link at the bottom of their newsletters. The Approved page is only available to you as an admin of your Cerkl.