Copied Documents folder much larger than original

Question

In setting up a new PC, I copied my Documents folder from my old machine to an external drive. The Properties dialogue shows this folder to be 19 GB and about 30,000 files. When copying to the new computer, Windows told me it was working on over 100 GB and over 100,000 files. I let the copying proceed, but it seemed to get hung up on a file called "archive", which I can't find at all in the backed up version.

I stopped the copying process, and when I compare the two directories, the new one shows 176 GB and about 114,000 files! Yet eyeballing the folders I can't see any difference.

I used File Explorer to do the copying. I selected all files in the backup folder and dragged them to the new folder.

Any help would be appreciated.

UPDATE (not sure if this constitutes an update, comment, or answer):

It seems that the Properties dialogue in File Explorer was reading the size of the backed up version incorrectly. The backed up version was on a WD My Passport Ultra external drive. While File Explorer said its size was in the 30 GB range, Windows PowerShell gives a size in keeping with the much larger copied (i.e. new) folder. I went back to the old PC, and sure enough the original directory was in fact much larger than File Explorer indicated the backed-up folder was on the My Passport.
So the (large) original folder was copied correctly to both the external drive and new computer, but for some reason File Explorer was incorrect in indicating a much smaller folder on the external drive, leading me to believe there was bloat in the final copied folder.

Answer 1

Does the Documents folder contain links, i.e. shortcuts, to files in another location, that are being expanded?

Are any files in Documents stored online in the cloud? You might be bringing documents from OneDrive, Google Drive or elsewhere.

Also, there is some increase of file size if moving to a HDD with larger allocation unit size. For example, a 1 kB file on a disk that has 4,096 byte allocation size takes up 4,096 bytes, the smallest size possible. If moved to a drive with 64 kB allocation, it takes up 64 kB, with most of that empty. Check allocation size settings for both drives.