The difference between Behind-the-Ear (BTE) and RIE hearing aids is that on RIC/RIE the receiver sits directly in your ear, while BTE hearing aids have the receiver built into the part that sits behind the ear.
Receiver-in-Ear (RIE) hearing aids
RIE hearing aids are due to their effectiveness and the ease of wearing have made them one of the most popular types of hearing aids. Receiver-in-Ear (RIE) hearing aids are also sometimes called Receiver-in-Canal hearing aids (RIC).