Sync: difference between Queued and Processed

Hey guys!

What is the difference between Queued and Processed in the sync process? I migrated from AWS S3 and transferred the bucket by hand. After all the images were “Queued” in the Sync tab, they started to appear correctly from GCP. But I have 30GB of images, 500K files (32K gallery items) and the process looks like it will take at least two months at the current rate, making my site very slow.