These three terms appear constantly in apostille-related materials. They are not interchangeable.

Authentication is the process. Apostille and certificate of authentication are the two possible outputs. Ontario's ODS issues an apostille when the destination is a Hague member, and a "certificate of authentication" when the destination is non-Hague. The same office, the same verification step - two different certificates depending on where the document is going.

This creates confusion when someone asks for "a Canadian authentication" without specifying the destination. For EU countries, the answer is an apostille. For the UAE, the answer is an authentication plus embassy attestation. Confirming the destination's Hague membership before submitting anything prevents this mistake.