The Mac’s Photos app can take up a lot of storage space—actually, it’s not the app itself that uses up space, but its database of images that you have imported into Photos. So naturally, when you need to free up storage space, one way to do that is to delete photos from the Photos app.
Say you deleted some photos in Photos, but now you need to get those photos back. And what if, after deleting those photos, you added some new ones. So now you want to restore the deleted photos, while at the same time, preserve the just added ones. Can it be done?
Yes, but it requires a little finesse. You will also need an external drive with enough storage to restore your entire Photos Library.