No, it downloads what it needs. If you restore everything, of course, it downloads a lot.
If it says anything about “whole backup” as opposed to less-versus-more, please cite.
Subfolders have nothing to do with how much it downloads. It needs blocks, that’s it.
EDIT:
Here is another explanation of the backup process. There were several others cited.
How the restore process works explains that though some details had been omitted.