Cost can mean money spent. However, it can also mean some sort of sacrifice. "Queen Elizabeth I's success as a monarch came at the cost of her personal happiness" = She sacrificed her personal happiness to attain success as a queen. Expense can also be used to mean sacrifice, but it is more often used in formal accounting language. Expenditure almost always refers to money and is also used in formal accounting language. The difference between expense and expenditure in accounting is that expense refers to some necessary cost of doing business, whereas an expenditure refers to any type of payment. Examples of expenses would be rent, food, maintenance on a car or payment of interest on a loan. An expenditure might be the purchase of a business, a new building. Example: A business buy a new truck to make deliveries. The payment is an expenditure - it is only made once. After that, the money needed to keep the truck fueled and to repay the loan would be an expense. They would keep occurring over time.