Hallo,
SNC protects your data (in transit): Secure Network Communication.
SSO allows you to, for example, to get you into a SAP instance without entering your password after you have authenticated against, for example, the Windows domain: Single Sign On.
You can use SNC without SSO, they are not necessarily connected, e.g.
Configuring SAP SNC without Single Sign-On on UNIX/Solaris/Linux
Regards
Thomas.
