The difference function returns the portion of the primary geometry that isnt intersected by the secondary geometrythe logical AND NOT of space. The difference function only operates on geometries of like dimension and returns a collection that has the same dimension as the source geometries. In the event that the source geometries are equal, an empty geometry is returned.

Difference returns that portion of the first geometry that is not intersected by the second.

Symmetric Difference of Geometries

The symmetricdiff function returns the symmetric difference of two geometriesthe logical XOR of space. The source geometries must have the same dimension. If the geometries are equal, the symmetricdiff function returns an empty geometry; otherwise, the function returns the result as a collection.

Symmetricdiff returns the portions of the source geometries that are not part of the intersection set. The source geometries must be of the same dimension.