He is deployable in both land and space. The only difference between the games is in space. Darth Vader flies his TIE Advanced X1 in EaW, but in FoC, he flies in his flagship, Executor. In the first Empire campaign mission, where Vader chokes an Imperial Officer, and when you lose in conquest mode, where Vader chokes an officer, which is actually the player.
Vader knows no mercy . He shows no fear, and kills his soldiers when they fail.