As far as the graphics output is concerned, PDF is strict superset of PostScript. In fact the "PDF page description language" is PostScript constrained to only

As far as the graphics output is concerned, PDF is strict superset of PostScript. In fact the "PDF page description language" is PostScript constrained to only drawing operations which have somewhat extended semantics, as PDF drawing model does Porter-Duff composition while PS does not. In all, when you rewrite any piece of PS code delimited by /showpage into shortest PS reprasentation without control structures you get valid PDF representation of exactly same final page image.