In an IPCC Enterprise environment the ICM scripts are for call routing and resource selection. Calls are classified by an DN, associated with a Call Manager CTI ROute Point. The ICM then assigns a Call Type based on the DN. Call Types are used to determine which ICM script are run during a call. The ICM scripts are stored on the Logger node of the ICM Central Controller.
The CRA scripts, specifically IP IVR or Queue Manager, are stored in the CRS Repository of the CRA Engine. These scripts are primarily used for MoH and Call Treatment. A CRA Script is called from a step in an ICM Script.
A good place to start getting an overview of IPCC Enterprise is the Design Guide. I have provided a link to it.
http://www.cisco.com/en/US/products/sw/custcosw/ps1844/products_implementation_design_guide_book09186a008057a473.html
