File Size differences when copying from Macbook to WD passport drive

Just purchased a WD My Passport Drive for Mac (2TB). Works fine out of the box. However, just curious why it shows big differences when copying files to the drive. I copied 550GB in photo/image files to the 2TB drive, and it shows 1.8TB remaining, only 200GB used?

When comparing File info folder by folder, it shows the same number of files copied including file sizes on both MacBook and the drive, just the available size on disk remaining is confusing?

Any thoughts?

Hi dmedici,

What is the version of your Mac OS?