The equatorial radius of Earth is approximately 6 * 103 km, while the equatorial radius of Saturn is approximately 6 * 104 km. What is there difference

If by 104 and 103 you meant 10^4 and 10^3 the difference would be 10 because you subtract them as exponents and get 10^1 which is just 10. If you meant 104 and 103 as they are then the difference would be 6 as 104 x 6 is 6 more than 103 x 6.