WordApplication.Save

Overload	Description
Save(Document, String)	Writes a Document to a file.
Save(Document, System.IO.Stream)	Writes a Document to a stream in the form of a Microsoft Word document.
Save(Document, System.Web.HttpResponse, String, Boolean)	Streams a Document to an HttpResponse with the option of having it open in the user's web browser. The fileName specified will appear in the browser window. In addition, the content-type to use when streaming the file is specified.
Save(Document, System.Web.HttpResponse, String, Boolean, String)	Streams a Document to an HttpResponse with the option of having it open in the user's web browser. The fileName specified will appear in the browser window. In addition, the content-type to use when streaming the file is specified.

Overload	Description
Save(Document, Microsoft.SharePoint.SPDocumentLibrary, String, Boolean)	Writes a Document to a file and saves it to a SharePoint Document Library.
Save(Document, Microsoft.SharePoint.SPListItem, String)	Writes a Document to a file and saves it to a SharePoint List Item.