Hello,

Change in supply and changes in quantity supplied, though both terms sound the same, they have a lot of difference.

Change in supply is a term which denoted that something has differed in supply, either the supplier has changed or the item ordered has changed or anything else.

Whereas changes in quantity supplied means that number of items that one receives are changed. Suppose a person orders 20 boxes and receives only 18. This means that the changes in quantity supplied.

If we discuss the effect on supply curve, then,

Changes in supply shifts the curve leftwards or rightwards

Changes in quantity supplied shifts the curve upward and downward.

Best Wishes.