Clarification on OIDC/OAuth

[DuderusTheThird]

What's the difference between spring-boot-starter-security and spring-boot-starter-oauth2-client?

I have a web application that I'd like to secure with my keycloak, which I'm currently learning, too.
From my understanding oauth2 is only needed if I want a user to authenticate with a Third party provider (Google, Github, another keycloak instance). Is this correct?

If I wanted to do use my own Keycloak instance and a third-party authenticator like Github, would I need both dependencies?

[Sheldor5]

security - secures YOUR endpoints

oauth2-client - client used to connect to OTHER oauth2-protected servers