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.
FLAC is the audiophile's handshake: CD-perfect sound at roughly half the shelf space. Free Lossless Audio Codec: think ZIP for sound: it decompresses back to the exact original. That makes it the right destination when what you need is archiving music with zero quality loss and a genuine size saving.