The actual braking force is the actual force generated by the brake system, and is measured using a dynamometer. The difference between the theoretical braking force and the actual braking force is due to losses in the brake system, such as friction between the brake pads and the caliper, and drag in the brake fluid.
Brake efficiency is an important factor to consider when designing a brake system, as it affects the overall performance of the vehicle. A higher brake efficiency means that the vehicle will be able to stop more quickly and efficiently.