Question

The world record for the longest journey driven by car is 626,960 km. The longest journey by tractor is 21,199 km.

Answer 1

If you round both numbers to ten thousand car would be 630,000 and tractor would be 20,000. Approximate means estimate and not exact.
630,000-20,000=610,000
The approximate distance is 610,000.
Miles=  379,036

Answer 2

The answer is 605,761 because when it says difference you must subtract.