The buttons ’Intersection’ ( ) and ’Intersection with line’ () construct the intersection of an arbitrary object with a plane or a line.
In the first case the result is a curve, in the second one or more points.
This command makes sense to construct intersections with locus-surfaces or groups. In the case of groups there is a difference to the button . While the latter intersects the line or plane with all objects of the group one-by one, the former intersects the group as a whole.