Reaction distance and braking distance are not same. Both are a bit different.
Reaction distance is distance the vehicle travel before stepping on the brake. So, reaction distance is the distance your vehicle travels when the driver realize and react to a hazardous situation and apply the brake.
Braking distance is distance the vehicle travel after applying brake and it finally stop. So, braking distance is the distance your vehicle travels after the driver applies the brakes and the vehicle finally stop after few distance.