AI - Adobe Illustrator EPS - Encapsulated PostScript (EPS) is a standard file format for importing and exporting PostScript files. It is usually a single page PostScript program that describes an illustration or an entire page. The purpose of an EPS file is to be included in other pages. Sometimes EPS files are called EPSF files. EPSF simply stands for Encapsulated PostScript Format. - Prepressure.com Both are actually Vector Image Formats used to define images that are created in Vector Formats. Vectors are basically images formed by means of lines and points, which allows them to be resized to any size, as the lines are equation dependent. Used mainly in Printing and High Quality Publishing.