M4A vs MP3

M4A is a file container format, while AAC is the audio codec inside it. An M4A file almost always contains AAC-encoded audio. Think of M4A as the wrapper and AAC as the audio compression algorithm inside.

Yes, most modern Android devices and apps support M4A playback. However, some older Android devices or budget players may have inconsistent M4A support, where MP3 would work reliably.

M4A (AAC) typically sounds better than MP3 at the same bitrate, especially at lower bitrates like 128 kbps. At 256 kbps or higher, both formats sound very similar and most listeners can't tell the difference.

No — converting between lossy formats causes generation loss, adding additional compression artefacts each time. The resulting MP3 will be slightly lower quality than the original M4A. Convert only when necessary.

Apple chose AAC (delivered as M4A) because it produces better quality than MP3 at the same bitrate, which improves the listening experience especially on its own hardware. Apple has been a key proponent of AAC since the iPod era.