Q: Can you XenMotion a VM between an Intel and AMD system?
A: No. You can only XenMotion a VM between systems with the same processor manufacturer and type.
Q: Does XenMotion require you to have the same exact configurations for your server systems?
A: While you do need to have the same type of processor in each system, other configurations can differ. You can have different amounts of memory, different storage controllers, and different network controllers in each system.
Secondarily, Citrix is giving away for free with XenServer a remarkable number of enterprise features, including the enterprise console to manage multiple hosts (XenCenter), the VM live migration (XenMotion) technology, the resource sharing (Resource Pools) technology and the enterprise storage management technology.