Some of these don’t even give you any visual approximation of the printed result (e.g. article editor systems used by some newspapers). Authors get a plain text editor where they type their article (a real “word processor”), and indicate special attributes to some of the content (headings, bylines, etc.). The system uses a styleguide which is applied to the entire publication, probably out of control of article authors (somebody else does the visual editing, as per the traditional separation of journalists and typesetters), and has precise information about layout (so that you’ll be told if a heading is too big to fit into the column for an article, for instance; then you have to change your heading to fit).
For those systems which do give you a visual layout system, they will (if properly set up) have very precise representations, and control, of how the page will lay out.
One thing that these systems will have in common, if the editor really knows what they’re doing, is that they don’t style/layout a document by playing “suck it and see” with the content. That’s the amateur’s approach. A professional will understand the processes involved, including the manner of writing articles, the interaction of the editing process with the printing process, and its limitations. You may get away with the amateur approach for a document with only a few pages, but you couldn’t print an entire magazine that way; and even something like a five page document becomes painful if you have to manually fiddle with it everywhere.