The Sojourner rover with the Mars Pathfinder used a entry, descent, and landing system involving airbags to land on Mars. The Spirit and Opportunity rovers each used more-or-less the same system involving airbags to land on Mars.
The Curiosity rover with the Mars Science Laboratory (MSL) used a very different landing system, including "seven minutes of terror".
Why did NASA engineers select such an apparently complicated landing system for MSL?
How do rocket scientists calculate the impact forces for a Mars landing for a given proposed landing system, when no one has ever used that landing system on Mars ever before?
How do aerospace engineers choose a landing system?