Continuing on with what the other poster said, when run as an "app" it then also eliminates the regular address bar and other buttons that are common on a full web browser so it "feels" more like a native app. There's also metadata that the app can use to add to the "jump list" feature of the Windows taskbar. You can then also get added as a target to "share" on Windows. There's a number of features that you get access to as an installed PWA at least on Windows compared to just being a webpage in the browser.