Hello Rizwan,
All these 3 solutions are coming with one and the same license. The difference is that with Kerberos SSO for example, you will not be able to offer secure authentication from outside corporate network because the Kerberos technology is valid only for the intranet, you will not be able also to apply strong authentication like two-factor authentication or risk-based authentication, you will not be able to use our Mobile SSO, and other. With SAML you will be able to achieve Mobile SSO and all the other capabilities.
If you want we can organize a presentation of the SAP Single Sign-On product and we will be able to explain these three supported scenarios for you and your team. If you are interested just send me a message on donka.dimitrova at sap.com.
Regards,
Donka Dimitrova