Distinguish between a change in demand and a change in quantity demanded?

This is based on the principle of an economics demand curve. A change in quantity continues to move along the same demand curve, whereas a change in demand shifts it either to the left or right of the original line. A change in the quantity or amount demanded is brought about by a change in the price of the item. For example, a price hike or sale. A change in demand on the other hand, is caused by other variables such as a change in tastes, income or competition from related goods.