When a document has some section properties like orientation or page size and the document is printed with virtual printer, the generated PDF does not preserve the section properties. 

For example, if the document has Landscape orientation set, in the generated PDF file, the page with Landscape orientation is visualized with Portrait orientation and the text is drawn vertically.
If the document has some page size set, for example A5, in the generated PDF file, the page with size A5 is visualized as page with A4 page size.