Geo-Join Nearest

Hello, first time question poster here and new to Dataiku. I've replicate a flow that I created in another tool which uses geo-join in a prepare recipe to find the nearest location between 2 lists of locations with long & lat data points. When comparing the output of Dataiku with the output of the other tool, I am noticing some different matches on nearest location as well as some variations in the distance between the same 2 locations. In order to account for the differences, I'm seeking to understand the methodology of the Dataiku geo-join for nearest location, but I haven't been able to find any documentation or references to it. Does Dataiku use a linear/straight-line distance between 2 points to geo-join, shortest driving route, or some other approach?

Any insights into this would be much appreciated. Thanks!

Operating system used: Windows