Command and Conquer: Red Alert 2 contains 2 playable factions, Soviets and Allies which both previously appeared in Command & Conquer: Red Alert. Red Alert 2's single player campaign is structured in an alternate-ending modediametrically opposed to a progressive story mode.
Command & Conquer: Red Alert 2 contains two distinct story lines depending on which faction the player wishes to play as. Both of the story lines differ in several distinct ways. However, the Allied story line is canon due to the way in which the expansion pack continues.