The Activity application entry point

Activity was originally the only application entry point that Unity supported and because of this it’s highly stable in the majority of scenarios.

This application entry point is appropriate to use in the following scenarios:

• Your project uses plug-insA set of code created outside of Unity that creates functionality in Unity. There are two kinds of plug-ins you can use in Unity: Managed plug-ins (managed .NET assemblies created with tools like Visual Studio) and Native plug-ins (platform-specific native code libraries). More info
  See in Glossary that must run on a Java thread. For more information, refer to Plug-in compatibility.
• You’re upgrading an old project that already uses the Activity application entry point.

If these scenarios don’t apply to your project, the GameActivity application entry point is a more appropriate application entry point. Among other benefits, Unity’s implementation of GameActivity gives you more control over the interaction between Android and your application.

Additional resources

• Set the application entry point for your Android application