What makes a $100 SSL certificate better than a $10 certificate?

A DigiCert certificate goes for a $100 / year, a QuickSSL certificate for $69, but you can get a RapidSSL for $10. So what's the difference?

From a technical standpoint, there's no difference. A certificate is a certificate. The main reason they are priced differently is because the companies issuing the certificates spend different amounts of time and resources verifying that you are who you claim to be. The cheaper companies generally only make sure you own the domain the certificate is being issued for while the more expensive ones, like DigiCert for example, also verify the company behind the domain name. This means they need to check the corporate registry in your country to verify that your company actually exists and that you are some how connected to that company.