sp2010 plan authentication methods

Authentication modes — classic or claims-based

Authentication modes determine how client computers authenticate with SharePoint Server 2010 resources.SharePoint Server 2010 supports two types of authentication modes : Classic and claims-based authentication mode.

SharePoint Server 2010 supports three authentication methods windows,form-based and SAML windows based authentication 

Classic based authenticaton supports only windows based authentication .

Claims based support windows,form-based and SAML windows based authentication  .

References :

http://technet.microsoft.com/en-us/library/cc262350.aspx
http://technet.microsoft.com/en-us/library/cc262350.aspx

http://sp2010classicmodevsclaimsbased.blogspot.sg/