The question is much clearer, thanks.
It's a good question and I think the reason for this behavior is:
1) When we move files with in the same volume (does not matter which sub-folder), the files do not move, just the pointers are changed to reflect the new file location.
Any meta-data processing follows serialization logic (kahuna domain, can run on only 1 cpu) : Depending upon the FILER's load at that give moment (CPU,Memory,Network : Type of workload ), it is always going to take some extra time compared to copying files.
2) When we copy files : The file attributes are not copied, only the file is copied and files inherits the permissions of the new location. File copy can make use of the multi-processing cores and therefore I am not surprised with your observations.
I tried my best to explain but I think it's more complicated than that, especially how CPU Domain processing works.
Hope this helps.