There would be times when a site would appear different to site collection admins and the Read only users. The first troubleshooting step in this would be:-
1) Check if the home pages is properly published..
2) If yes, then check its master page and make sure it is published and approved. This will make the changes visible for all users.
3) Check if the images, stylesheets, etc. are not in minor version formats or draft formats.
4) If the page still appears different then make the following changes in the style library.
5) change the versioning settings of style library to show draft versions to users with read access.
6) Above step should be taken if the draft versions cannot be located and are rooted deep down in the library's hierarchy.