What is the difference between IdentifyTask and QueryTask?

[DeonaEvans]

Could someone please remind me what this difference is?  I can't find it in the documentation.  Thanks!

[BjornSvensson]

The main difference to me is that Identify works off a full map service, while Query works on a single layer (or table) in a service.

Many of the properties are also different (partly because of the above difference).

[DeonaEvans]

Okay, thanks.  It's also my understanding (and experience) that the layerDefinitions that you can apply on the IdentifyTask doesn't work in 9.3.1 but will work in 10.  Do you know anything about that?

[BjornSvensson]

Yes, see the thread:
http://forums.arcgis.com/threads/19661-FindParameters-layerDefinitions

Or the REST What's New (for 10) at http://help.arcgis.com/en/arcgisserver/10.0/apis/rest/whatsnew.html
"Identify and Find operations now support a new layerDefs parameter."

Or our updated doc for IdentifyTask - layerDefinitions property: "Requires ArcGIS Server 10.0 or above."