OAuth2 vs sso: What are the differences?

OAuth2: An open standard for access delegation. It is an authorization framework that enables a third-party application to obtain limited access to an HTTP service, either on behalf of a resource owner by orchestrating an approval interaction between the resource owner and the HTTP service, or by allowing the third-party application to obtain access on its own behalf; sso: Buzzfeed's single-sign-on authentication proxy. The authentication and authorization system BuzzFeed developed to provide a secure, single sign-on experience for access to the many internal web apps used by our employees.

OAuth2 and sso can be categorized as "User Management and Authentication" tools.

sso is an open source tool with 2.11K GitHub stars and 110 GitHub forks. Here's a link to sso's open source repository on GitHub.