MP3 is an audio format that can compress and encode an audio file. It uses the lossy compression algorithm to contain audio data. The lossy compression helps to reduce the data significantly without losing audio quality. MP3s are created using different bit rates maintaining the original quality.
M4A is an audio file format developed by Apple, often used for songs and other audio content in iTunes. It is based on the AAC codec and offers high compression with minimal loss of quality. M4A is ideal for digital music files due to its smaller size and efficient storage.