Synchronize your files and folders, even with command line options, using DirSync Pro
DirSync Pro (Directory Synchronize Pro) is a free, small, and relatively easy to use program for file and folder synchronization.
It can be used to synchronize the content of select folders recursively. You can also use it for incremental backups.
With DirSync Pro you can synchronize files from your desktop PC to your USB-stick.
DirSync Pro supports also command line options.