Your are you going to take memory (aka cache ... and even that is a bit of a definition stretch .... but it is the closest thing to "memory" on a HD) from one HD to another ? HDs have platters for storage and store magnetically and cache which is basically a chip like a DIMM or SSD....these can not be transferred from one physical drive to another.
If he was referring to partition sizes on a single disk, that would be different but he said he had two hard disks , not two partitions.
You can also transfer files from one disk to another simply by using copy / paste but again, that is not what was indicated.
If we have a language barrier and term misuse, then we need toi better understand what is being attempted.