Different image format is meant for different configuration scheme. RBF and RPD are raw binary file which you will need to write your own script to program it into FLASH memory. RBF is meant for Passive Serial / Fast Passive Parallel configuration scheme whereas RPD is meant for Active Serial Configuration Scheme.
Please take a look at user guide for the basic understanding. You may refer to Cyclone V configuration handbook for more information about configuration scheme and the image format:
https://www.intel.com/content/dam/www/programmable/us/en/pdfs/literature/hb/cyclone-v/cv_5v2.pdf