SSL certificate DigiCert Secure Site Pro EV

If you want to protect your domain in the national language (e. g. 百度.中文网), then you will need to order a certificate with IDN support.

Certificate with extended validation (EV), such as Comodo EV SSL, VeriSign Secure Site with EV.
This is the same as for the standard certificate; the organization has many data to check. The peculiarity of these certificates is that the browser address bar is highlighted in green while entering a secure website. It means the highest degree of reliability.

Certificate with high level of Server Gated Cryptography (SGC) - such as Thawte SGC SuperCert orVeriSign Secure Site Pro with EV (SGC).
Those certificates are used if your clients have the old browser versions. Thus the high level of encryption will be used even in the browser support absence.

You can use one certificate for many domains instead of ordering many certificates.