Editor will have a screen stylesheet. Normally this would be below the doctypes subfolder in the custom directory. You can find out what this is by executing the following on the command line in Editor:
response(get_custom_dir())
Publishing Engine will similarly have composition stylesheets located in its custom directory. It is possible that these are the same as the ones used by Editor, but there are lots of reasons they might be different. It is possible that they have the same contents but are stored in different "physical" locations on the network. It is possible that their contents are different, too since the requirements for authoring and printing can be so varied.
I don't remember the subtleties of how Editor requests and PE provides the list of available composition stylesheets, but I do think the .dcf file Editor uses can play a role. This file is also usually located in the custom folder Editor uses.
Folks on the Adepters mailing list where lots and lots of Arbortext users, admins, and developers hang out 24/7/366 (it is a leap year, you know!) could probably provide more information than I have here. Information on joining that list (as well as pointers to lots of other Arbortext resources) can be found here:
http://blog.single-sourcing.com/top-arbortext-resources
Good luck!
