Distance
Calculates the geographic distance between two geometries as follows:
 Points—Returns the distance between the two points.
 Lines—Returns the shortest distance between the two lines.
 Polygons—Returns the shortest distance between the two polygons. For example, if the polygons are two lakes, the distance would be between the two closest shores.
Option Name  Description 

Distance units  Specifies the unit of measurement to use to calculate the distance. One of the following:

Geometry 1  The field that contains the geometry to compare with Geometry 2 to determine the distance between them. This field also accepts geometries that are generated by stages in Spectrum Spatial Routing, such as a LineString or Polygon. 
Geometry 2  The field that contains the geometry to compare with Geometry 1 to determine the distance between them. This field also accepts geometries that are generated by stages in Spectrum Spatial Routing, such as a LineString or Polygon. 
Distance  The name of the field that you want to contain the distance returned by Spatial Calculator (output type is double). 