I can't believe I have to ask an elementary question such as this. :)
No apology necessary. Those terms are usually confused & used loosely. The term "Realtor" means you belong to the National Association of Realtors.
The real distinction is between broker & agent. An agent must work for a broker who reviews & signs off on the agent's paperwork. The broker gets the full commission & then splits it with the agent. So if you are an agent you must split your commission with your broker. However, if you are a broker, & complete the deal yourself, then you get the full commission. A broker can own their own company & complete sales/purchases on their own.