What are the differences among a routine, a combinaison, a variation and choreography? Please, help me to clear up. Welcome to any reply.

a routine - Is choreography set to a particular song. Something that you would perform (Usually in a performance or showcase) by yourself on the floor with your partner or team in the case of a formation.

a combination - Is a small set (2-4) of patterns (basic, twinkle, chasse, etc.) that you do in order. Example, an open box, followed by twinkle, followed by outside turn.

a variation - Is a slightly different way of doing a pattern. In Swing, leading an outside turn with the right hand instead of the left. Waltz box with closed feet, versus passing feet.

choreography - Is where you map out the complete or larger set order of patterns that you are about to do. This can include body language, such as facial expressions. Usually done to any old song, unlike a routine which is usually to a specially picked song. Best example, is in a group class when the instructor has you do to about 10 patterns in a row, one leading to another that's choregraphy.

Hope this helps, and any corrections are welcome

By the Way, it's never a mistake when you mess up doing a pattern, it's a variation.