The Playstation 2 has the same basic design as that of the Playstation. The major difference is the the analog nature of the four shoulder buttons and the joysticks. This allows variable motion as opposed to constant motion experienced with controllers of the past generations.

Despite the innovation, not many games for Playstation 2 make use of the analog buttons. Many players don't even realize they're analog because they still look and feel like their predecessors.

ControllerTimeline