Question: What is the difference between a Identity Provider and Connection?
Google (the company) is an Identity Provider. Google knows who you are (via your username and password) and can tell a service provider that you really are who you say you are.
The social login connection to Google is a connection. It uses the OAuth2 protocol to connect to Google, and this protocol is what is used to tell the SP (your app) that you really are who you say you are.
It’s important to note that Social login connections can go to many IDPs.