sorting photos from different cameras by creation date

As a guess, I'm betting that one of the cameras may have treated a change in time zone differently than the other. So the two cameras are always off by a constant amount. So the trick is to decide which one has times you like, and change the other one to match. Figure out how much they differ, and then in Photos select-all of the "to-be-fixed" pictures, and go to"Photos>Image>Adjust Date and Time..." and change the time you see by the needed amount. All the pictures will be changed by the same interval. You may have to tweak a bit-- I usually mess it up the first time. I've done it a lot.

Are you talking about the image's internal metadata creation date 'DateTimeOriginal' (important)? Or the image's macOS file system creation date 'FileCreateDate' (not important but a cause of lots of confusion here)?

You can copy the former to the latter with 3rd party tools like GraphicConverter, A Better Finder Rename etc. Then Finder would sort them in its list views based on the file system dates which would then be in sync with the metadata dates.

Are the photos you want to sort in a folder in the Finder or in an album in Photos for Mac?

I am asking, because you wrote you copied photos into a folder, but in Photos we can only add photos to albums, not to folders.

To separate your photos according to the camera, you could use seat albums with the rule "Camera model is ...". Then select the photos, where you need to adjust the timezone in the smart album for this camera model.