OpenId is the protocol to negotiate authentication and get back an access token that your app can verify that it comes from your openId authority so that you may trust the information in the ticket - like the user-email maybe - or some claim that the user is admin or the like.

OpenIdConnect is a standard built on top of OpenId that makes setup much easier.

Even if every OpenId Authority has their own naming on endpoints etc - they can explain what their own way is in the OpenIdConnect contract

https://pidpq.perrigo.com/.well-known/openid-configuration