Hi - I purchased a 2TB SSD to move my catalog and backup files to and free up space on my iMac. Since this was a new SSD it had 2TB indicated all of it was available when I did a Get Info. I copied the LrC backup folder to the SSD. This folder indicated it was using 433GB (due to a large preview file). After the copy, which was very fast, only 1.2TB was available on the SSD and it showed ~722GB used. The LrC folder on the SSD shows 433GB just like the one on the Mac.
Does this make sense? Anyone have ideas what is taking up the extra space? I don't see any other files on the SSD.
The 433GB consists of what files and folders? The Backup folder, which you refer to, should not contain previews, so its not clear what you moved and what you did.
But anyway, no one here knows what is taking up space on your new SSD. You however, can examine (in great detail, if needed) what is taking up space on the new SSD and then come to a much more definitive conclusion than some strange across the internet can come up with.
This is probably a glitch. Since Apple introduced the new APFS formatting, it seems that the Finder has great difficulties showing the correct size of packages and folders. I recently increased the number of smart previews in my catalog from about 10% of all images to 100%. According to Lightroom, the size of the smart previews package increased from about 30 GB to about 300 GB, which is exactly as you would expect. But the Finder is still telling me that the smart previews package is 30 GB...