One is widely supported and familiar. The other excels in modern streaming and low-bitrate performance.
AAC: compatible, widely used.
Opus: excellent at low bitrates.
| Feature | AAC | Opus |
|---|---|---|
| Compatibility | Excellent across devices and platforms | Good, but not universal everywhere |
| Low bitrate quality | Good | Excellent, especially for speech |
| Latency | Moderate | Very low (good for calls) |
AAC is the safe default. Opus is often technically better for modern streaming scenarios.