This is a format created in the Acorn Draw program, intended for image visualization by using vector lines. It’s used for storing information in the publishing business (brochures, logotypes, etc.). The main advantage is it’s high quality source images when printing. It’s been in use since 1980.
PNG is a raster graphic data storage format that uses lossless compression algorithm to Deflate. PNG was created as a free format to replace GIF. PNG supports three main types of raster images: grayscale image, a color indexed image and the color image. PNG format stores graphical information in a compressed form.