[strcat]

GrapheneOS and CalyxOS are very different. GrapheneOS is a hardened OS with substantial privacy/security improvements:

https://grapheneos.org/features

CalyxOS is not a hardened OS. It greatly reduces security vs. AOSP via added attack surface, rolled back security and slow patches. CalyxOS does not have features like this. It does the opposite of this.

Compatibility with Android apps on GrapheneOS is also much different. GrapheneOS provides our sandboxed Google Play compatibility layer:

https://grapheneos.org/usage#sandboxed-google-play

Can run the vast majority of Play Store apps on GrapheneOS, but not CalyxOS with the problematic microG approach.

https://eylenburg.github.io/android_comparison.htm is a third party comparison between different alternate mobile operating systems. It could include many more privacy/security features but it's a good starting point.

https://privsec.dev/posts/android/choosing-your-android-base... is an article with more long form comparisons between OSes.