Kerberos / Needham-Schroeder usually refers to an authenticated encryption protocol that uses symmetric keys (shared secrets). It lets two parties who have never communicated, but who both mutually trust some third party, establish one another’s identities and negotiate a symmetric key for encrypted communication.

The SAML core is an XML-based system for serializing, signing, and encrypting assertions. There are also SAML flows, and they likely use something Kerberos-esque. So SAML is to Kerberos what HTML is to HTTP, or what x.509 is to TLS, or something like that.