OGG is the free spirit of audio: open, patent-free, and quietly brilliant at looping game sound. It was born in 2002, the Xiph.Org Foundation, and its real weak spot is everyday device support: car stereos and Apple hardware mostly shrug.
MP3 is the format that taught music to travel: small, scrappy, and welcome absolutely everywhere. MPEG-1 Audio Layer III. Perceptual coding: it throws away the parts of the signal your ear is least likely to miss. That makes it the right destination when what you need is playing on anything with a speaker, from new phones to twenty-year-old car stereos.