I am having a hard time in understanding the concept of OpenId and OpenId Connect. Both of them have the word "Open" in them but there is a difference in the meaning. Why is this so?
THere is no difference in the word "Open" per se.
OpenID and OpenID Connect are both authentication protocols standardized and overseen by the OpenID Foundation, thus the similarity in name.
OpenID is an authentication protocol designed for federating identity from the ground-up, and for nothing else.
OpenID Connect is a standardized authentication layer on top of OAuth 2.0, which is an authorization protocol standardized separately. OpenID Connect was a response to the fact that many people were using OAuth for authentication, and the use case needed to be properly codifed and supported.