There is also 2 different type of write off.
Statuatory write off which is when a structural member of the car has been damaged and there for is not repairable.
&
Repairable write off which is when it is still possible to repair the car but it is not economically viable to do so through the insurance company.
This is when the cost of repair is close to or more than the value of the car they pay out the value of the car.
Some companies will let you keep ur car and deduct the value of the wreck from the payout figure and some may just take the wreck off u.
Thats my understanding anyway, had my vn writen off Dec last yr for repairable write off