Answer. Diesel oil consists of C13 to C15 carbon atom while fuel oil consists of C15 to C18. The boiling range of diesel oil varies from 250°C to 350°C. While, boiling range of fuel oil varies from 350°C to 400°C. Diesel oil is used as a fuel in buses, trucks, railway engines, tube well engines and other heavy transport vehicles. While, fuel oil is used in ships and industries to heat up boilers and furnaces