Output is defined as the amount of products created in a certain amount of time for a company no matter what it will be used for. When a company decides to increase their output, they usually have to put more money into it. This is because they need more money for the raw materials and labor to make more of these products.
A marginal product is when a modification has been made due to a change in the input. Sometimes, all inputs can be equal. This would mean that the total cost of producing a given level of output will be minimized when the ratio of marginal product to input price is equal for all inputs. This would occur when changes are being made to the output.