Buffer couplings are mechanical devices used to connect two rotating shafts while allowing for some misalignment and absorbing shock loads. They help protect machinery from damage caused by sudden changes in torque or speed, making them ideal for applications where vibrations or impacts are common. Chain couplings, on the other hand, consist of two sprockets connected by a chain. They provide a flexible connection that can accommodate misalignment and are often used in heavy-duty applications. Chain couplings are known for their durability and ability to transmit power efficiently, making them suitable for various industrial settings.