MS Word and Powerpoint can print a page with a vector graphics object to PDF Creator and the resulting PDF file will retain the vector nature of that graphics object. For instance, it may be zoomed to very high magnification without loss of resolution - circles stay circles. Other programs don't work that way. Print from Inkscape, Scribus, or PDF XChange Viewer to the same PDF Creator "printer" and these same types of graphics are apparently converted to an image, which is compressed, resulting in the usual compression artifacts.
Am I correct in assuming that the programs that can print through PDF Creator to leave object graphics as vector graphics are embedding those commands in the postscript they send to the printer? Or is PDF Creator interacting with the MS programs in some other way to achieve this?