Is a wave that occurs by a one time disturbance or one event.
Is a wave that reoccurs in specific intervals or has regularly repeating disturbances.
Is a wave that occurs when a spring is compressed and released, the disturbance is in the same direction as which the wave travels.
Is a wave that occurs when a spring is pulled sideways and is released, the disturbance is at a right angle to the direction which the wave travels.