OAuth is an open standard for authorization.
OAuth provides secure delegated access (Party A authorizes User, and Party B trusts what Party A tells them).

The user's credentials are validated, the user is given an Access Token, and that Access Token is trusted going forward.

Access Token: a token identifying an application

Id Token: a token identifying one user

A bearer token is a type of access token used with OAuth 2.0

A bearer token is an opaque string (it has no meaning to the Client encoded into it).