They are just a bookmark, but on Windows, they become a first class citizen on your task bar. If you are the type to have a ton of tabs open across many window

They are just a bookmark, but on Windows, they become a first class citizen on your task bar. If you are the type to have a ton of tabs open across many windows, this also makes the "app" easier to spot. You can also pin the app to the taskbar and have it launch with Windows.