Actually the difference is the radios in the device. The Centro 685 uses a GSM radio which is more prevalent in Europe and good for travelers. The Centro 690 uses CMDA which is used by Sprint but doesn't work in the UK for instance (which I discovered on a business trip this year).
About 685 miles.
The distance is straight path from one place to another place. There might be slight difference between the actual distance and the above mentioned distance because of the route chosen.The distance between the above mentioned places is 685 miles approximately.
685 miles
The driving distance is about 685 miles.
About 685 km or 425 miles
685 nautical miles
It is: 685/1
685
685 - 548 = 137
About 685 miles.
685 rounded to the nearest integer is 685.
1, 5, 137, 685