This is common question in caclubindia. i have found some interesting example.
it can help CA or CMA aspirants.
"Take a supermarket, which spans across different types of merchandise like grocery, cosmetics, apparels etc. A Chartered Accountant will be able to tell what the revenue from each of the departments is, what is the profit/loss at the company level, department level, and the tax payable on the income earned. A Cost Accountant will evaluate the rationale as to why a particular unit showed up loss, which product needs to moved out of the shelf, which product needs to be stocked up more, what is the price at which a product ought to be priced in order to make the required margins, how to manage the costs efficiently, so that though the sale price cannot be augmented, the cost can be condensed to keep up the margins. A cost accountant facilitates an organization to improve performance by analyzing the business."