Domain Validation (DV): This is a lower level of validation. The CA validates that you have control of the domain. A DV certificate expires in 90 days.
Organization Validation (OV): A higher level of validation. The CA validates whether or not the company is valid, if it is registered, and if the business contact legitimately works at the company. The CA uses your organization information to verify you legally own or have the legal right to use the domains listed in your certificate.
Extended Validation (EV): The highest level of validation in which you must have signed letters and notaries sent to the CA before signing. Wildcard certificates cannot be EV certificates because an EV certificate requires you to be explicit about all the subject alternative names (SANs).
Jackie Chen's IT Workshop 