Activity was originally the only application entry point that Unity supported. As a result, it's highly stable across most scenarios and is compatible with the majority of Unity features.

If you use Activity, your application player loop runs on a Java thread. This means that you can call Java APIs like

myLooper

from plug-ins.

If you use Activity, Unity uses the Android Java

Choreographer

. This helps you to understand how frame synchronization occurs in your application.