Maybe I'm missing something obvious, but....
Say I have a photo in Organizer that I want to fix. But the fix is beyond Organizer's abilities--e.g., to remove a small defect. So I use the Editor button to open the file in Elements Editor 2021 and Heal the defect.
Is there some way this fix can immediately be reflected in the photo I have open in Organizer--the one I hit the Editor button for? The only option seems to be to save the corrected photo in Editor with a new name, and then add that new file to Organizer, yielding what are basically two copies of the same photo (the original and the fixed one). In OS X Photos, when I open a photo in an external editor (e.g., Luminar), all the changes are immediately applied to the original (non-destructively), but if it's possible to do the same with Elements (Organizer+Editor) it's not obvious to me.
I think you'll find that Photos in macOS also creates a new copy of the image after you've made any changes to it. Photos keeps a "master" copy (the original photo) so you can always revert back to it, but it isn't displayed in the Photos app, and the "master" copy gets hidden away in the macOS file structure.
Photoshop Elements works in a similar manner but is much more explicit in how you work with multiple versions of the same image. Version Sets allow you to hide the original and any other previously edited versions if you wish to keep the Organizer tidy.
While saving the file Editor, please de-select the 2 checkboxes highlighted in below screenshot. Your work will get overwritten on existing file, and new copy won't be created.
Please let me know if this solves your issue.
Well, no. As I note in my original question, that Photos applies the changes NON-DESTRUCTIVELY: I can make the modifications--even using a third-party editor--then undo them, even months later; this is probably the most important part. And of course, with Photos I don't have to re-import the photo I just sent out for a quick fix as even changes made by a non-Apple product are automatically recognized and applied while preserving the version history; in Elements, once a photo is sent to the Editor Organizer essentially forgets about it.
The thing I was hoping for was actual integration between the two applications that are sold as a single product but seem to have have nearly no recognition of each other. I figured I had to be missing something obvious, that Adobe wouldn't be selling a product with such a clumsy workflow resulting from a near-total lack of integration between its component parts.
I think I know where you're going wrong and what's causing your confusion as to how Photoshop Elements works. Hope you don't mind the lengthy explanation that follows.
1. Here is the Elements Organizer which shows the thumbnail previews of all the sample images in my Catalog.
2. I've selected the first image in the Catalog and gone to Edit > Edit with Photoshop Elements Editor. That has opened up the first image in my Elements Editor. The screenshot shows both the current state of the Organizer and the Editor side-by-side. Notice the red bar with the yellow padlock and the message "Edit in Progress" across the image in the Organizer indicating that this image is now locked as it is being edited.
3. Now I've done some quick edits to my image in the Editor but I've not saved the image yet so the thumbnail image in the Catalog has not changed yet.
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4. I've finished editing the image so I'm going to save it now using File > Save. It's the first time I've saved this image so the Elements Editor has automatically given it a new name, DSC_0185_edited-1. This is important as I don't want to overwrite the original image, DSC_0185. It is also automatically choosing to save it in the JPG format as I haven't created any layers in the Editor. Had I done so, then the Elements Editor would have selected the PSD file format instead.
5. Notice now how the first thumbnail image has been updated in the Elements Organizer after I have saved my Edits. I still have the image open in the Editor, so the image is still locked, but the Organizer is already aware that I have made some changes to the image and has updated the Catalog to reflect that.
6. Now I've closed the Editor and I'm looking at my Catalog in the Organizer. The thumbnail of the first image has been updated to reflect my changes and notice there is also a new little icon on the top-right of the thumbnail. If you hover your mouse cursor over the icon you will see a tooltip which says "Version Set". A Version Set is a collection of images which contains the original image and any edited versions of that image. You can read more about Version Sets in the Organizer User Guide.
7. To see all the images in the Versions Set you need to ensure that you have enabled the View > Details option. When you have that option all images that are part of a Version Set will now have an small arrow icon on the right-hand side of the thumbnail.
8. Click that arrow to expand the Version Set to show all the images in the Version Set. I also find it helpful to enable the View > File Names option too. As you can see the screenshot below, in this Version Set are two images - the first one is the edited image, the second one is the original image. If you go to Edit > Version Set there are a number of options available to you to manage the images in the Version Set, including reverting back to the original.
I hope that helps you better understand how the Organzier and the Editor work together in Photoshop Elements. If the process seems a little complicated, please remember I'm just using all the default settings, leaving Elements to make all my choices for me, which makes things very fast and simple. As Somya has pointed out in his reply above, there are further options to choose from when it comes to saving images that you might want to explore.