Kerberos is a comprehensive authentication architecture designed for strength and embedded in all participating clients, servers, and applications. It will serve to provide common authentication credentials but is in no way an architecture designed to provide strong authentication. Strength of authentication will be determined by the individual servers and applications just as it is now except the weakest link will jeopardize the others. Based on cryptographic credentials which are decrypted by separate user and server passwords that don't cross the wire.
Encryption depends upon application.
Single Sign On. You login once and have access to everything. Underlying protocol obtains credentials for participating services as needed. Same Sign On. You must manually login for each service but the usernames and passwords are the same for each.