X.509 certificates include certain information about the certificate owner and the public key. This information will allow the other side to verify the authenticity of the certificate owner and the integrity of the certificate itself. The verification can be done by humans, with the help of a computer. X.509 certificate has a private key, which is normally stored separately from the certificate for security reasons.
Since the associated key is stored separately, the SSH key contains a public key only. It does not contain any information about the key owner. Neither does it contain information that will let one reliably validate the authenticity and integrity.