What is the difference between the Multiple Listing Service (MLS) and the consumer website REALTOR.ca?

The Multiple Listing Service is a cooperative system used only by REALTOR® Members of Canada's real estate boards. It is accessible to any REALTOR® Member who has agreed to represent your
interests and share remuneration from the transaction with a cooperating REALTOR® Member. The MLS contains detailed information and numerous search tools, all designed to match people with the properties that fit their exact requirements. REALTOR.ca is a website operated by the Canadian Real Estate Association (CREA) that displays an abbreviated version of most listings uploaded to the MLS system.

Source: Toronto Real Estate Board (TREB)