A ROM is a binary package representing the code plus electronics that is normally in an Intellivision cartridge for emulation. ROMs can be a single ".rom" file or a combination ".bin" with a ".cfg" bundle. Older and smaller-sized games in the range of 6k or less tend to only have .ROM, while sophisticated and newer games that stretch to 42k and beyond are .bin+.cfg because the emulation OS needs instructions in the cfg on how to map/swap the game in Intellivision memory to play. Note: an "int" or "itv" file may be a renamed "bin" with a different name for modern computer operating systems to associate with launcher apps.
Media Links:
youtu.be/R0h6H5A3b6Y
Source Links:
www.reddit.com/r/intellivision/comments/kcniyc/int_vs_bin_vs_rom/