The level of the assurance mostly depends on the certificate validation type, the amount of the information the certificate applicant provides to the Certificate Authority (Comodo). The deeper the certificate validation process performed by Comodo is, the higher assurance is.
Domain Validation (DV) SSL certificates provide low assurance and medium assurance. To issue a DV certificate, a Certificate Authority should verify whether the certificate applier can manage the domain name the certificate is activated for. The certificate validation process is fast enough. Usually, it takes up to 15 minutes. Low assurance certificates provide the same security and encryption level as the other ones and are not limited in any way. They are good for blogs and personal websites. They are the following: PositiveSSL, PositiveSSL Multi-domain, PositiveSSL Wildcard.
Medium assurance certificates are suitable for small, medium-volume business and personal websites. You can check these certificates here: EssentialSSL, EssentialSSL Wildcard.
SSL certificates that provide the high assurance level are Organization Validation (OV) ones. For a certificate issuance, it is necessary to complete the Domain Control Validation (DCV), and the Certificate Authority should verify the legal and physical existence of the company that applies for the certificate. The certificate validation process may take up to 2 business days. High assurance certificates are a good solution for medium and large-volume websites.
The list of high assurance certificates: InstantSSL, InstantSSL Pro, PremiumSSL,Unified Communications,PremiumSSL Wildcard,Multi-Domain SSL.
Extended Validation (EV) SSL certificates provide the very high assurance level. One should submit the documents required by the Certificate Authority to verify the certificate applier. Also, it is required to verify the legal and physical existence of the company and its telephone number to complete the certificate validation. These certificates are best for large-volume e-commerce websites and large organizations. Additionally, the green bar with the company details will be available with EV certificates: EV SSL, EV Multi-Domain SSL.