rsync -aivr --delete --progress /src/my-files/ /dest/my-files

# rsync walks the src drive
# if a file is present in src that is not present in dest, then copy the file to dest
# if a file is present both in src and in dest, then compare modification times
#     and overwrite using the later one.
# if a file is present on dest but is not on src, then copy the file from dest to src.