When Norton Toolbar shows a status of a website as This page is Secure, that means the business (as an owner of the website) has been validated as a legal business entity and the web site uses recommended security practices including best-of-breed SSL Certificates and daily web site malware scanning. The validation process goes through a company which issues security certificates.
When Norton Toolbar shows a status of a website as This page is Safe, that means the website has been tested by Norton, and that no malware or other known threats have been found.