WHAT ARE THE DIFFERENCES BETWEEN A WILDCARD AND A SAN SSL CERTIFICATE?
There are several important differences between a Wildcard and SAN certificate. Although both have wide coverage, the Wildcard is significantly more limited than a SAN solution.
A Wildcard will only offer protection to the subdomains where the wildcard character is placed. So *.SSL247.co.uk will cover blog.SSL247.co.uk, secure.SSL247.co.uk, etc. However a SAN can cover multiple items that don’t share the same domain name (domain names and subdomains). For example one SAN certificate will cover SSL24.co.uk, SSL247.net, new-SSL247.net etc., as well as a whole host of other services including OWA, ActiveSync, Outlook Anywhere, Autodiscover, POP3, IMAP4 and Unified Messaging.
A wildcard however will offer you security for an unlimited number of subdomains, whereas SANs are limited dependent on the certificate you choose.
Yet for the best protection possible you should choose a certificate with Extended Validation (EV). This is only available with a SAN certificate, making Wildcards less secure.
In fact Wildcards are not recommended as a primary security solution