Patching opatchauto apply vs opatch apply

I am automating patch application with Ansible, and I have some basic questions about patch application.

For GI (RAC or Restart)

Should you always use "opatchauto apply"?

When should you use "opatch apply"?

Scenario, when applying a JDK patch to the DB Home, either opatch apply or opatchauto apply work. Applying the same patch to the GRID Home however, only opatchauto apply method works. (patch readme only talks about opatch apply)

Any documentation on opatchauto vs opatch would be appreciated.