If one looks at the component motives of any melody, the successive repetition of the motives becomes apparent. Repetition is also used in chord progressions and in patterns of dynamics and timbre. Whole phrases and sections of music often repeat. The following illustration represents musical repetition. Variation means change of material and may be slight or extensive.
Variation is used to extend melodic, harmonic, dynamic and timbral material.
Contrast is the introduction of new material in the structure or pattern of a composition of music that contrasts with the original material. It is most often used in the latter areas of phrases or sections and becomes ineffective if introduced earlier.