ODG is not the most common vector image file format. Its developer is the OASIS group, and the name is an abbreviation for OpenDocument Graphic File. ODG vector images are set using dots, lines, and curves, and saved using XML markup. As a rule, ODG files are considered optimal for creating, editing and storing drawings, vector images and logos. To create such files at the moment most often use the popular free office suite Apache OpenOffice and LibreOffice.
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.