Veslink Distances does not always have the same routing preferences set as does the IMOS Estimator.
When the IMOS Estimator sends the route it wants to draw to Veslink distances, it does not send the detailed route it calculated, but rather a sequence of ports and passing points. The detailed route is then recalculated by Veslink Distances, but it is not guaranteed to adhere to the same preferences.
In short, the comparison between the two systems is not like-for-like. IMOS takes into account the client's settings, while Veslink uses a more general set of inputs, as it knows nothing about the client’s settings in IMOS.