The native OMG format is a proprietary format and is structured very much like EPUB3, both are based on the HTML5, CSS3 and SVG standards. In some areas, OMG captures a richer set data than EPUB3.
Omegadoc Designer stands out from other DTP applications in many ways: 1 - One click export of fixed-layout eBooks in two popular formats: EPUB3 and Amazon KF8 (Mobi) formats. 2 - Styling modeled after CSS3. 3 - Superior multiple-page viewing capability. 4 - Intuitive and easy to use GUI.