MP4 is the world's default video: the file that plays before anyone has to think about it. It was born in 2001, the MPEG standards group, built on Apple's QuickTime design, and its real weak spot is very little day to day: as a container its quality depends on the codec inside.
OGG is the free spirit of audio: open, patent-free, and quietly brilliant at looping game sound. A container usually carrying Vorbis or Opus audio, both open and royalty-free. That makes it the right destination when what you need is games and open projects that want seamless loops and zero licensing strings.