In traditional back kicks, the fighter first cocks the kicking leg, leaving him or herself open to a kick from the opponent. The sport version does not open the leg as widely and keeps the knee in closer to prevent any counter kicks and to facilitate a speedy back kick.
Traditional roundhouse kickers cock the knee of the kicking leg, and then snap the leg out, while leaning forward. This invites a quick counterattack to the open and defenseless body. The sport version keeps the knee turned toward the inside for a powerful close-in roundhouse kick. This allows the kicker to kick inside of the opponent's roundhouse attempt.
The traditional spin side kick is too wide, unbalanced, and leaves the fighter unprotected. In the sport version, the fighter brings the knee in close and snaps the kick out in a whip-like fashion, while lowering the body so balance is easier to maintain. If the fighter is combating a roundhouse kick, there is no need to block since the body is already lower than the opponent's roundhouse.