git clone:
Will physically download the files into your computer. It will take space
from your computer. If the repo is 200Mb, then it will download that all
and place it in the directory you cloned.
git remote add:
Won't take space! It's more like a pointer! It doesn't increase your disk
consumption. It just gets a snapshot of what branches are available and their
git commit history I believe. It doesn't contain the actual file/folders
of your project.