Transferring photos and videos from Mac format hard disc to Windows laptop.

I'd export "loose" images and movies to exFAT formatted external disk and then copy them to Windows. That should be faster and more robust.

A regular file copy does not change .jpg to another codec.

But I don't fully understand where the images are now stored on the Mac: a) Inside Photos library or b) as "loose" .jpg etc images in Finder folders? Notice that iCloud Photos is about the same Photos library and iCloud Drive is about the same as "loose" images in Finder folders.

If the images are inside Photos library or iCloud Photos, then you should export them via File > Export either as originals or/and as edited versions, whatever you desire. Then copy them to Windows. The Photos library will then act as a backup until you verify the images are correctly moved to Windows.

Adding to what Matti said: When you use File>Export>Export nn Photos to generate picture files on your ExFAT drive, you get to choose what format you want. Edited pictures files are created in the export process, so you can choose format, quality, size and even the filename you want:

Choosing "Moment Name" will let Photos put the pictures in folders based on date and location. I just tried it with a few pictures and got this:

Pretty helpful, I think.

If you choose File>Export>Export Unmodified Originals, then you have no choices about format, size, etc, since you get the original files just as they were imported to Photos originally. They also can be put into "Moment Name" folders.

Personally, I would want both edited versions and originals. But if you have pictures that were never edited, and you've already exported those as originals, then there's little point in creating new files for them with Export nn Photos. You could make a Smart Album with only Edited pictures and export those.

Let us know if we need to clarify…