Oversupply is when there are more goods on the market than consumers are willing to buy.
In the case of goods, surplus is the period when overproduction of a good reduces the price of that good to a point where producers lose money.
Oversupply is usually corrected through production cuts or discounting, but the time period over which this occurs may be longer or shorter depending on market dynamics.
Oversupply may persist longer when prices and volumes are less flexible due to market conditions or government price controls.