PostScript is a page description language (PDL English, page description language), used in many printers and conventional manner, such as transport format graphics files in professional print shops. It is based on the work done by John Gaffney at "Evans & Sutherland" in 1976. The PostScript concept differed fundamentally by using a full programming language to describe a print image. Image that would later be printed on a laser printer or other output device quality, rather than a series of escape sequences of low level (this seems to Emacs, which exploded internal concept similar with respect to editing).
Portable Network Graphics (PNG), is a raster graphics file format that supports lossless data compression. PNG was created as an improved, non-patented replacement for Graphics Interchange Format (GIF), and is the most used lossless image compression format on the Internet. PNG supports palette-based images (with palettes of 24-bit RGB or 32-bitRGBA colors), grayscale images (with or without alpha channel), and full-color non-palette-based RGB[A] images (with or without alpha channel). PNG was designed for transferring images on the Internet, not for professional-quality print graphics, and therefore does not support non-RGB color spaces such as CMYK.