When Scott McCall discovered his werewolf powers after being bitten in Season 1, he noticed his strength was greatly enhanced. He once threw a lacrosse ball so hard it broke right through a goalie's mesh net. Also he once hit his head against a wall out of stress causing some tiles to shatter with Scott suffering no damage to his skull.
Derek Hale is born a werewolf and more capable. Thus, he is much stronger than Scott physically, allowing him to overpower the younger, newer wolf.
The senior members of the Alpha Pack, Deucalion, Kali and Ennis each had tremendous strength, far superior to any other werewolf. Their overwhelming strength came from their having killed their previous packs to absorb their power and from being in a pack made up of multiple alphas.
Deucalion, the Demon Wolf, exhibited the greatest display of super-strength. He was able to overpower both Jennifer Blake, the Darach, and Derek simultaneously.
In 4x12 - Smoke and Mirrors Derek evolved, being able to shapeshift into a full wolf. His power having reached its zenith, he was able to destroy a berserker with his bare hands.