What's the difference between unmercied and unmerciful?

Unmercied

Definition:

Example Sentences:

(1) Wasikowska is fantastic as Robyn, her unmerciful eyes and contained silence emanating a determination, a commitment to her independence, and a derision for the life she's left behind.
(2) We did, after all, invade Libya with the Americans and hounded Gaddafi unmercifully until he was killed by his own people.
(3) From this unlikely base, Kirchner built a power structure that made him the undisputed leader of Argentina during an era marked by what seemed to be his three main obsessions: the trial of human rights violators; the redistribution of income; and a protracted war with Argentina's main media companies, which angered the Kirchners by reporting unmercifully on corruption during their presidencies.

Definition:

(a.) Not merciful; indisposed to mercy or grace; cruel; inhuman; merciless; unkind.

Example Sentences:

(1) Wasikowska is fantastic as Robyn, her unmerciful eyes and contained silence emanating a determination, a commitment to her independence, and a derision for the life she's left behind.
(2) We did, after all, invade Libya with the Americans and hounded Gaddafi unmercifully until he was killed by his own people.
(3) From this unlikely base, Kirchner built a power structure that made him the undisputed leader of Argentina during an era marked by what seemed to be his three main obsessions: the trial of human rights violators; the redistribution of income; and a protracted war with Argentina's main media companies, which angered the Kirchners by reporting unmercifully on corruption during their presidencies.