The differences between the shared SSL and the dedicated SSL is that the shared SSL is shared with the other domains on a shared server within your hosting environment. Whereas the dedicated SSL is dedicated to your website.
When you use the shared ssl the URL that appears in the browser to your customer will have the shared SSL name; for example: https://yourdomain.authsecure.com ** Where as in dedicated SSL you will see your domain name that is https://www.yourdomain.com/
With the shared SSL you get the benefits of SSL without the costs that are usually associated with setting up a SSL.
With the dedicated SSL you need to purchase the SSL certificate and a dedicated IP address that is assigned to your domain.
**authsecure.com is the name of the shared server that CRE Hosting uses for its' shared customers - if you don't host with CRE Hosting the name of your shared SSL will be different.