As per your question there is no difference. EBA = Exclusive Buyers Agreement. This is a contractual agreement between a broker (agent) and consumer (buyer) that basically says that the agent will represent the buyer and provide services involving the processes in purchasing real property.
EBA could also be "Exclusive Buyers Agency" If a broker advertises that they are an EBA, they are saying that they only represent buyers and do not represent sellers. (Do not list homes)