Certificates differ in how much the authority checked before issuing. The encryption is identical in all three - what varies is the verification, and what browsers do with it.

DV - domain validated

Proof that you control the domain. Issued in seconds, automatically, free from Let's Encrypt. This is what the overwhelming majority of sites use, including large ones.

OV - organisation validated

The authority also checks that the company exists, using registry records and sometimes a phone call. Takes days and costs money. The organisation name is inside the certificate, where nobody looks.

EV - extended validation

A heavier legal check, more documents, more days, more money. It used to produce a green bar with the company name in it, which was the whole selling point.

Browsers removed the green bar. Chrome, Firefox and Safari all show an EV certificate exactly like a DV one, because studies showed users did not notice it and it was being abused by companies registered specifically to obtain it. The visible advantage no longer exists.

So which one

  • Almost every site - DV, automated, renewed by a timer. Nothing else changes for a visitor.
  • Regulated sectors - OV or EV where a compliance requirement names it. That is a paperwork reason, not a technical one.

What actually affects trust

The domain name, the content, a working contact page, and the site not being broken. None of these is a certificate property.

openssl s_client -connect yourdomain.com:443 < /dev/null 2>/dev/null \
  | openssl x509 -noout -subject
# CN and O are all a visitor could see, and they will not look
Spend the certificate budget on automated renewal instead. An expired EV certificate is a far worse experience than a valid DV one - see renewal that silently fails.