Find what you just added
Every other timeline sorts by the date a photo was taken, which is lovely for reminiscing but hopeless for finding the ten photos you imported an hour ago. Recently Added flips that: it orders your library by when each photo actually arrived, so the newest additions sit right at the top.
That makes it the first place to look after a big Google Photos import, an AirDrop from a friend, or restoring a backup — the fresh arrivals are already waiting for you, on the web and in the mobile app.