rsync is described as 'Software application for Unix which synchronizes files and directories from one location to another while minimizing data transfer using delta encoding when appropriate. An important feature of rsync not found in most similar programs/protocols is that the mirroring' and is a very popular File Sync tool in the backup & sync category. There are more than 100 alternatives to rsync for a variety of platforms, including Windows, Mac, Linux, Android and BSD apps. The best rsync alternative is Syncthing, which is both free and Open Source. Other great apps like rsync are FreeFileSync, Duplicati, TeraCopy and Rclone.
Cannot sync between 2 local directories.