Difference 1: These certificates are used for the purpose of Authentication, not Encryption. If they get compromised, bad actors can impersonate certain entities for some time, but they cannot decrypt any prior recorded traffic to these entities.
Difference 2: If something happens to these keys, the CA can simply revoke the validity of the public key. This is a major pain in the _ for everyone involved, especially since all downstream certs needs to be re-issued and signed, but it's manageable. A built-in key that is somehow algorithmically included in every encryption mechanism, cannot easily be changed when it's leaked.
Difference 3: There is no single "highest Certificate Authority", so there is no single key to compromise the whole system.
Difference 4: These keys are ordinary asymmetric keys. They are not built-in backdoors into the system.
Difference 2: If something happens to these keys, the CA can simply revoke the validity of the public key. This is a major pain in the _ for everyone involved, especially since all downstream certs needs to be re-issued and signed, but it's manageable. A built-in key that is somehow algorithmically included in every encryption mechanism, cannot easily be changed when it's leaked.
Difference 3: There is no single "highest Certificate Authority", so there is no single key to compromise the whole system.
Difference 4: These keys are ordinary asymmetric keys. They are not built-in backdoors into the system.