ECONOMIC VALUE ADDED (EVA) measures the difference between the return on a companies capital and the cost of that capital. A positive EVA indicates that value has been created for shareholders; a negative EVA signifies value destruction.
ECONOMIES OF SCALE is based upon the theory that the more you produce of a good, the less that it costs for each additional unit, i.e., efficiency. Specifically, it is the reduction of the costs of production of goods due to increasing the size of the producing entity and the share of the total market for the good/product.