add the following SSJS code to a computed field on an xpage and render it on the server
return session.getNotesVersion();
That will tell you the version and fix paks.
You also might try getting the html of the locally rendered XPage and the html of the server rendered xpage and save those to a two seperate text files.
You can then add the text files as file resources an application in DDE and then select them both, right click and choose "compare with each other" to see if the server is rendering something different than the local preview.
It seems as if there IS something different about the server. Settings, version, config. Something