BetterAudio vs Background Music: both give Mac apps their own volume and pause music when other audio plays. BetterAudio adds EQ, routing and dictation.
Both give each Mac app its own volume, boost quiet apps and pause your music when another app starts playing. Background Music is free and open source but still in alpha; BetterAudio adds EQ, per-app output routing, media keys and dictation.
Pick Background Music if: You want a free, open-source tool that only does per-app volume and auto-pause, or you run macOS older than 14.6.
Pick BetterAudio if: You also want EQ, routing each app to its own output, media-key control or dictation.