Adobe explains why they offer two similar printing technologies PS and PDF. How these technologies differ from each other ? Adobe PostScript vs. Adobe PDF
When you hear people say that PDF is a "replacement" for PostScript, what they most likely mean is that PDF is a replacement for saved PostScript files and EPS files. PDF is not a replacement for the PostScript language or the PostScript processors that live inside of printers, imagesetters, and platesetters.
PDF can be used as a replacement file format for EPS, and that PDF can be used as a delivery format for sending complete publications to press. It is also suitable for soft-proofing, distribution on the Internet, and file archiving, as it is completely self-contained. But to print PDF, it is best to print to a device with true Adobe PostScript capabilities to get the highest quality output.
When you hear people say that PDF is a "replacement" for PostScript, what they most likely mean is that PDF is a replacement for saved PostScript files and EPS files. PDF is not a replacement for the PostScript language or the PostScript processors that live inside of printers, imagesetters, and platesetters.
PDF can be used as a replacement file format for EPS, and that PDF can be used as a delivery format for sending complete publications to press. It is also suitable for soft-proofing, distribution on the Internet, and file archiving, as it is completely self-contained. But to print PDF, it is best to print to a device with true Adobe PostScript capabilities to get the highest quality output.