As the documentation states the “KeepSourceFormatting” option does not preserve the style from the source document.
The “UseDestinationStyles”, does not enforce the exact style that is in the source document.
Our requirement is the following:
We have 2 documents with 2 completely different style in each of them. We need to create a third document with the exact styling form both documents.
If the first document is Calibri(10) and the second is Calibri(11), the destination document must have Calibri(10) and Calibri(11).
When using the UseDestinationStyles option, if a matching style already exists in the destination document, the style is not copied and the imported nodes are updated to reference the existing style.
The drawback of using UseDestinationStyles is that the imported text might look different in the destination document comparing to the source document. For example, the “Heading 1” style in the source document uses Arial 16pt font and the “Heading 1” style in the destination document uses Times New Roman 14pt font. When importing text of “Heading 1” style with no other direct formatting, it will appear as Times New Roman 14pt font in the destination document.
Using the KeepSourceFormatting option allows to make sure the imported text looks in the destination document exactly like it was in the source document. If a matching style already exists in the destination document, the source style is copied and given a unique name by appending a suffix number to it, for example “Normal_0” or “Heading 1_5”.
The drawback of using KeepSourceFormatting is that if you perform several imports, you could end up with many styles in the destination document and that could make using consistent style formatting in Microsoft Word difficult for this document.
Using KeepDifferentStyles option allows to reuse destination styles if the formatting they provide is identical to the styles in the source document. If the style in destination document is different from the source then it is imported.