Your description suggests either or both documents have content formatted in ways that override the underlying Style definitions and/or the same Style names are used in both documents but Style the definitions differ.

You wouldn't have these issues if both documents had the same Style definitions and they weren't overridden with hard formatting. As it is, it seems you'll have to choose between retaining the source formatting or applying the destination formatting - you can't have bits of both. Or you could correct the Style definitions in either or both documents and ensure they're used correctly.

__________________
Cheers,
Paul Edstein
[Fmr MS MVP - Word]