I would like to know if I should restore my catalog from my old hard drive with Win7 to the new hard drive with Win10? BUT, I would like to keep all the photos stored on the old hard drive to keep the new one "clean". Does this make sense? Is it possible? I was thinking if i set my watch folder to the old drive, it probably wont pull in the albums, events, and keyword tags.
Yes, the old drive was C: with Win 7 on it. It was running slow, so I took it in. We added a new SSD with Win 10 on it. It is now C: The old drive is accessible and bootable as Win 7. The old drive my be a couple years old and has 1.56 TB free. The new drive (C:) since its a SSD has 133 GB free. We added the new drive to the old computer. Which I think is maybe 3 years old?
I have probably 20,000 photos on the old drive. Probably with duplicates, since the old Photoshop, didn't have the duplicates feature or handle Live photos from iphones. I made a "final" back up of my catalog on the old drive to my myBook which has 3.15 TB free.
OK. Nothing to be concerned about. I suggest that you restore your "final" backup from your external drive to a new folder on the old drive. Once the restoration is complete, you can delete the existing files from their current location. When you do the restore, you should probably check the option to keep the existing file structure. For complete instructions to perform the Restore process, look here.
Also, what is the difference between importing from Apple iphone and camera/card reader?
There is no difference. Your iPhone is treated as a camera by the Adobe Photo Downloader. However, if you have not done this recently, and you are using HEIC photos on a newer version iPhone, there are a couple of other issues that you need to consider, including making some changes to the settings on your phone.