New
#11
Just as a follow-through since OP is happy already -
I wouldn't know from Professional or Plus versions (I think those are v5 names, not sure) - My comments are based on experience with the V6 (current) free and paid Home versions and, more specifically, the Macrium Knowledge Base I linked to.
There is no compression going on there, only relocation of data as necessary within the bounds of a maximum size allowed (constrained by target disk size) and a minimum size allowed (constrained by the amount of data already in the source partition).
An example: If you have an oversized 4th partition needing resized you might have a 5th and 6th partition remaining to fit on the disk and, in that case, you would resize that 4th partition on the fly to an amount below maximum in an amount equal to or less than the size of the 5th and 6th partitions combined. Did this on the phone with another forum member on the phone recently (while restoring an image, not cloning, but it works the same).