Final answer:
The difference between a shift in the demand curve and a movement along the demand curve is that the former is caused by external factors, while the latter is solely due to changes in the good's own price.
Step-by-step explanation:
The difference between a shift in the demand curve and a movement along the demand curve pertains to what causes the change in the quantity demanded of a good or service. A shift in the demand curve occurs when a factor other than the price of the good itself changes, leading to a new demand curve.
A movement along the demand curve, on the other hand, is the result of a change in the price of the good itself. When the price increases, the quantity demanded decreases, and this is represented by moving up along the demand curve, which is a contraction in demand.
It is important to note that a shift in one curve never causes a shift in the other curve. Rather, a shift in one curve, such as the demand curve, can cause a movement along the second curve, such as the supply curve.