Full screen one. Switch to the other. Now, use just cmd-tab and cmd-` to get to the full screen safari window (cmd-` switches between windows in the same application, which is literally never the right thing, but I digress).
For what it's worth, the third party tool 'altTab' mostly fixes this.
Bonus MacOS UI bug: I had to exit altTab to confirm they still hadn't fixed cmd-`. When I re-opened it using cmd-space, finder defaulted to the version in ~/Downloads instead of /Applications, then read me the riot act about untrusted software trying to change accessibility settings.
One more thing: I'm still not using MacOS 26, so all my complaints are about the "last known good" release.
Except Safari, which just fills out the window's height vertically. Kinda weird to make an exception like that but I don't hate it, because I generally use Safari for reading, and shrinking the browser's width forces lines of text to not get too long if the website's styling isn't setting that manually.
When I use the Window menu, Zoom replicates what double-clicking the top title bar does, while Fill maximizes the window. This holds true with the behavior you describe in Safari as well.
It just seems like a lot of apps treat Zoom and Fill the same now (I tried Calendar, Notes, TextEdit, and NetNewsWire), which adds to the confusion.
After I got used to working in windows instead of full screen all the time, I can't really go back. Even on Windows I find myself working the way I do on macOS. Full screening every app made more sense on a 1024x768 screen (or smaller). Once I moved to a widescreen display (which happened to coincide with getting my first mac) running full screen felt like the wrong move most of time.
Web pages would look something like this:
| <- whitespace -> | <- content -> | <- whitespace -> |
| | Lorem ipsum | |
| | dolor sit amet, | |
| | consectetur | |
| | adipiscing | |
| | elit. Morbi | |
| | convallis ante | |
Sorry if this comes across as disrespectful, but it smells like Stockholm Syndrome. You are choosing not to use the full extent of your screen estate, and that is your fine choice, but that is no excuse for making it hard. If you compound the whitespace, the thick borders and the generally oversized UI controls, not much of "productive space" remains available to get the work done. I am not interested in macOS as a content-consumption-first vehicle, though that's clearly where Apple is steering.
I am currently running a 16" display at a similar fractional scaled resolution (because Apple stopped understanding DPI after shipping the first LaserWriter, apparently).
Over that time, my eyes have not gotten better to match display DPI, so I'd rather have web sites just adjust the font size so that there are a reasonable number of words per line instead of rendering whitespace.
Non-full-screen windows would make more sense if Apple supported tiling properly, like most Linux WMs and also modern Windows.
MacOS sort of supports tiling in a "program manager shipped it + got promoted" sort of way, but you have to hover over the window manager buttons, which is slower than just manually arranging stuff. If there are any keyboard shortcuts to invoke tiling, or a way to change the WM buttons to not suck, I have not found them.
As for tiling in macOS...
You can use the mouse to drag windows into tiled positions. Grab a window and when your cursor hits the side, corner, or top edge of the screen, it will indicate the tiling position, much like AeroSnap on Windows from some years back. You can also hold the Option key while holding the window to get the tiling regions to show up without moving all the way to the edge.
Keyboard shortcuts exist as well. Go to Settings -> Keyboard -> Keyboard Shortcuts... In the dialog that opens, go to Windows. There you can see all the options and customize them if you'd like. Or set shortcuts for things that might not have one yet.
If for some reason dragging the windows around doesn't work, go to Settings -> Desktop & Dock -> the Windows heading. There are toggles to enable or disable dragging to tile, and the Option key trick. You can also turn off the margins on tiled Windows, which you'd probably want to do.
I've never been a big fan of window tiling myself. There was a time when I needed a lot of different windows visible at all times, but that hasn't been the case in a long time. I find tiling makes things too big or small, it's never what I actually want. I drag the window up to the top of the screen to invoke Fill from time to time, but that's about it.
That was the Mac in the 1990s. It was designed for, and highly usable with, a one-button mouse. It didn't have hidden context menus or obscure keyboard shortcuts. Everything was visible in the menu bar and discoverable. The Finder was spatially aware with a high degree of persistence that allowed you to develop muscle memory for where icons would appear onscreen every time you opened a folder.
There was almost nothing hidden or lurking in the background, unlike today (my modern Mac system has 500 running processes right now, despite having only 15 applications open). We've had decades of feature creep since the classic Mac OS, which has made modern Macs extremely hard to use (relatively speaking).
Why is it that some of the most useful features in Apple products are impossible to find on your own? I recently also learned about "three finger swipe to undo" in iOS instead of shaking the damn thing like it owes me money.
It works well for me, makes it easy to get two things side by side without wasting space.
Full Screen Mode was their answer to maximize, going back many years now (10.7).
Obviously all of that works better if Finder windows don't usually fill the screen, but it's not a hard requirement.
(IMO the spacial Finder was designed around floppies and small folders and didn't work so well with hierarchical folder views, so no big loss...)