In Ontario, a Commissioner of Oaths/Affidavits is an officer who has been granted the authority to ensure that an Oath or Affirmation has been administered in accordance with the law.  A Commissioner is regulated under the Commissioners for taking Affidavits Act. A Commissioner simply certifies that the process for taking the Oath or Affirmation has been administered properly.  A Commissioner cannot certify that the information contained in the document or statements is true. It is you, the person signing the document, who swears or affirms that the information contained within the document is true.  

A Notary Public on the other hand, is a public officer appointed under common law to assist the public with simple and non-contentious matters.  Every lawyer in Ontario is also a Commissioner. A Notary Public has all of the powers of a Commissioner but in addition to this, a Notary Public may administer Oaths or Affirmations, and authenticate the execution (witness your signature) of documents such as Affidavits, Statutory Declarations, Acknowledgements, Deeds and other conveyances, other out-of-province documents, verify identification and make true copies of same.  A Notary Public can verify that signatures, marks and copies of documents are true or genuine. This is known as a “notarization”. Notaries Public are regulated under the Notaries Act.