Both of these scenarios are alternate history scenarios. In Errand of Mercy, the Organians failed to stop the war with the Klingons and in The Undiscovered Country Kirk failed to stop the plot at the Khitomer conference. In both, the result is the same: the Klingons and the Federation are at war. Though it's impossible to tell from the screenshots, each scenario has a different Kirk graphic. In Errand of Mercy you get the TOS Kirk and in The Undiscovered Country you get the Kirk from the movies era.