Real Estate Buyer Agents

Can you tell the difference between a real estate buyer agent and an Exclusive Buyer Agent?
It can be very difficult, The national association of Realtors says any agent can be a buyer agent.
But can one agent promise to get the lowest price possible for one client and the lowest price for another client in the same transaction? It's not possible!
Read this following story to help clarify:
http://buyerstrust.com/exclusivebuyeragent/