Mileage difference between ECU/Nav 5 and odometer

[WindyChuffer]

My odometer is reading 4989 miles whereas the data bit on the Nav 5 is showing over 5000

So
Which one is correct and why is this the case ?

Anyone got any ideas or theories or better still facts

You cannot expect bike odo and GPS odo to tally if they both measure distance independently.

11 miles delta on 5000 is 0.22% difference. Noise.