The 37, 49, and 61-key models provide an assignable switch jack for connecting a damper pedal. The 25-key model provides a sustain button that implements the damper function.
On all models, you can use the octave buttons in conjunction with the key transpose function to play MIDI's entire range of notes. The 37, 49, and 61-key models provide pitch bend and modulation wheels.
The 25-key model provides a joystick that can also control pitch bend and modulation, as well as an arpeggiator function, giving you full control in spite of this model's space-saving dimensions, and providing a wealth of performance expression.