Why are the --sync and --no-sync options giving me same output in df

Why do the --sync and --no-sync options in the df command in Linux give me same output?

When I first ran the --no-sync flag along with df like this:

df --no-sync

and then I ran the:

df --sync

... flag, but both are giving me same output. So I Googled so much and searched on many sites but did not found any good solution.