If you have scripting/programming experience, you could set something up to delete the destination (copy) directory, then copy over the source directory. Then set the script up to run as a scheduled task.
Of course, this is inelegant, and not so practical if you're dealing with more than a few gigs of data.
You could, however, set up your script to compare the filesize and date modified for each file, and copy only the ones that have been changed. The script could also verify that a file exists in the source directory, and if it doesn't, delete it. That would be synchronizing.
There's probably a program out there that will do this for you, but it's so much more satisfying to do it yourself

. Plus, you have total control over the process.