There is a slight difference between SAML & OpenID Connect though they appear to be the same at times.

SAML - Security Assertion Markup Language

This deals with the sharing of XML responses between Identity Provider and Service Provider.

OpenID Connect

OpenID Connect is an authentication layer on top of OAuth 2.0. OpenID Connect is about the user authentication unlike, SAML which deals with sending and receiving XML responses between IP and SP about the user.

Hope this is helpful.