Capital - The investments of the owners and the accumulation of profits or losses for the business since it began. Income - The sources from which the business earns its money. Income is measured for a period of time. Cost of Sales - The cost of the product sold by a business and the related costs of having the product available to sell. In some instances service-technician labor is included in cost of sales along with the product sold.
Cost of sales is measured for a period of time.
The daily expenses incurred in running your business. They are the rent, advertising, insurance, etc. Operating expenses are measured for a period of time. Examples include bad debts recovered, interest income and expense, discounts earned, insurance on corporate officers, etc. Consult with your accountant for more information.