What is the difference: Coordinate System v.s. Spatial Reference?

[SuiHuang]

Hi Everybody:

    I am trying to create a script that takes coordinate system as an input, but after checking the list of data types I found that both Spatial Reference and Coordinate System types are suitable (see attached picture). Which should I use? or what are the difference between them?
    Thank you!

[LucasDanzinger · Accepted solution]

Check out this help page on Spatial References. The coordinate system, along with resolution and tolerance are properties of the spatial reference.

[GhislainPrince]

tl/dr version: they're the same.

Longer version: From the script tool standpoint there is no difference.

if your tool has a SpatialReference parameter, the user of said script tool will get identical experience to a CoordinateSystem.

Once upon a time they were different, the UI/user experience for these 2 types were different, SpatialReference had additional parameters (XY, Z & M Domains). That is no longer the case as of the 9.2 release.

For backward compatibility we kept both types, thought they are are interchangeable and basically identical.

You can glimpse a difference by doing arcpy.AddWarning(arcpy.GetParameterAsText(i)) in your script. They have different string values. But when you turn around and pass these values into other gp tools/arcpy api, the two slightly different strings behave identically.


SpatialReference string representation

GEOGCS['GCS_WGS_1984',DATUM['D_WGS_1984',SPHEROID['WGS_1984',6378137.0,298.257223563]],PRIMEM['Greenwich',0.0],UNIT['Degree',0.0174532925199433]];-400 -400 1000000000;-100000 10000;-100000 10000;8.98315284119522E-09;0.001;0.001;IsHighPrecision


While CoordinateSystem looks like this
GEOGCS['GCS_WGS_1984',DATUM['D_WGS_1984',SPHEROID['WGS_1984',6378137.0,298.257223563]],PRIMEM['Greenwich',0.0],UNIT['Degree',0.0174532925199433]]