I want to say that planchas usually involve some kind of springboard action or use of the ropes. "Tope" just isn't a word that is used much in NA wrestling. At least, not in the WWE.
Plancha is a splash-type move, like a high crossbody. Tope is a flying headbutt. Tope suicida is a headfirst dive to the floor on the opponent, which is actually what I think that move was, come to think of it.