There is no difference between stock and supply.

Ans. No, I do not agree with this statement.

Stock refers to entire quantity of a commodity which is in the custody of the seller. So it is the potential supply.
Stock depends on production.
Stock can be greater than the supply.
(a) For perishable commodities the stock and the supply can be the same.
(b) For durable commodities, the stock can be more than the supply.
4.      Order of existence
Stock comes before supply
Supply refers to the quantity of a commodity offered for sale at a given price and at a given time and place.
Supply depends on stock and price.
Supply cannot be greater than the stock.
(a)    Supply is either equal or less than the stock.
Supply follow stock there cannot be supply without stock.