Why huge pic folder got 3 GB huger when moved from Windows to Mac

I moved a 32.6 GB folder of mostly jpegs from Windows to Mac via a 64 GB Cruzer. I've tried opening some of the jpegs. They all opened. Everything appears to be in order. Besides jpegs, the folder contains some legacy Photoshop files which I hope to open via Affinity Photo. ( I gave up my PS CS6 because a Mac update killed it.) The 32.6 GB folder on the PC contained 9012 files and 237 folders, including subfolders and sub-subs. On the Cruzer, same count. Mac Info says only that the folder on Mac has 9250 "items." This makes perfect sense if items are files plus folders (9012 + 237 = 9249) plus maybe 1 invisible Digital ET (9249 + 1 = 9250). Here's the part I have major trouble with: The size of the 32.6 GB (on PC and Cruzer) folder is 35.51 GB on the Mac. That's a gain of almost 3 GB. A lot! Can it be explained by the Mac's generation of invisible (on Mac anyway) .DS_Store files, plus the retention of the newly visible though no longer functional Windows thumbs.db files? Or is it the weight of the invisible Digital ET? Ok, no, but one of you might have given that answer at this point if I hadn't beat you to it, and I am hoping for a more plausible answer--so, do you have one? Thank you for your time, smarts, and knowledge.