What's the difference between a real estate agent and a REALTOR®?

"REALTOR®" and "real estate agent" are not interchangeable, although some real estate agents might like them to be. The term REALTOR® is a registered certification mark that
identifies the quality of services rendered by licensed real estate agents who are members of The Canadian Real Estate Association (CREA). All real estate agents are not REALTORS®, but all REALTOR® members are real estate agents. REALTOR® members are committed to a strict code of ethics known as the REALTOR® Code, and are the only ones who have the right to list your property on the MLS® Systems of their local real estate boards. To correctly be referred to as a REALTOR®, a real estate agent must be a member of CREA.

Source: Ontario Real Estate Association(OREA)