Chiasmus is the reversing the order of words in the second of two parallel phrases. This rhetorical device is also referred to as reverse parallelism, antimetabole or syntactical inversion.
In rhetoric, parallelism means giving two or more parts of the sentences a similar form so as to give the passage a definite pattern.
In the end, the true test is not the speeches a president delivers; it’s whether the president delivers on the speeches. - Hillary Clinton