Crash report difference between Crashlytics and App Store Connect Analytics

[Aurelio P]

Hello, my application has Firebase Crashlytics reporting implemented, and I am noticing some large differences between the crash reports from Crashlytics and the Apple App Store Connect Analytics crash report.

Where Crashlytics report about 20 crashes, App Store only show 1 or 2, why are these crash reports so different? 

Is it all because of the "Opt-in" choice from iOS users? Or does it have some relation with crashes happening in Background? I know that Crashlytics shows crashes that happen when app is in background, but does App Store Connect do it?

I've tried searching for specific information about these differences online but haven't had any useful results yet, so any help would be greatly appreciated.

Thanks!