What's the Difference between PDF and PostScript
Before Adobe's founders got rich and famous they had worked for Xerox at the Palo Alto Research Centre. John Warnock and Chuck Geschke were up to their ears in page description languages, which are programming languages that describe page content above and beyond the basic bitmap. According to John Warnock, PostScript was designed to be a modern standard for electronic printing, and indeed that is precisely what it became. PostScript is a computer programming language which can integrate text and graphic data into a single content stream. This is part of the reason for its massive success in the graphic arts. Its wild child, the Portable Document Format, or PDF, is not a programming language but a data format. PDF was not originally designed or particularly intended for the graphic arts industry. Instead it was created for a whole other purpose. These are the two most important differences between PostScript and PDF.
But the story is more interesting than that. Originally PDF was intended to provide device, application, operating system and font independence for content. It was designed to be a vehicle for transporting content so that it could be viewed anywhere regardless of the computing platform. It placed no restrictions on the type of content, which meant that absolutely anything could be contained in a PDF, including dynamic content such as sound and video. So you could view all sorts of stuff including cartoons in a PDF. Of course the same was true of PostScript, even though such mad applications are hardly common in the graphic arts.
The clear distinction between these two technologies started blurring within months of PDF's introduction to the market. The printing community, already drenched in PostScript blood following years of making it work, embraced PDF to provide file independence as well as the device independence PostScript assured.
But the massive scope of PDF meant that it was extremely common for creators of PDFs to produce deeply traumatizing processing nightmares. Unconstrained PDFs contained all sorts of wicked mutant data that made it extremely difficult to get print-ready files through graphic arts workflows. An entire sector of the software industry had grown up around the PostScript frontier, as developers rushed to introduce preflight checking tools that would check, fix and report PostScript processing errors. PDF mayhem created yet further opportunities for software developers, who turned their attention to assisting with PDF file processing. The net result is an industry deeply wedded to Adobe PostScript and to PDF. The former has lost ground as the market has evolved and PDF has come to dominate graphic arts workflows.