PDF is short for Portable Document Format, which can be translated from English as “Portable Document Format”. It was developed by Adobe Systems for use by US federal authorities as a tool for storing working documents. This is a universal cross-platform format, which is now standard for electronic documents. It serves to convert text files (including photographs or other images) into electronic documents without any loss. To read PDF files you need special programs - Adobe (Acrobat) Reader, PDF-Viewer and others.
PS is one of the common vector image formats. The PS format (full name - PostScript File) was created by Adobe Systems. A vector image that is saved in the PostScript page description language usually contains both text and vector or bitmap graphics. Files of this format can be directly printed without opening an application by a printer that supports PostScript. This dynamic typed programming language is best known for describing pages in the publishing industry. Now the PS format is being actively replaced by the more popular PDF.