Yes, it's a regional thing. In Puerto Rico we use almost exclusively "violeta" for "purple" and when you say "morado" or "púrpura" it sound as if you're reading an old play or something like that. Usually the Spanish you learn in Rosette Stone is very formal and the Spanish we speak in Puerto Rico is very familiar so you sometimes get weird looks when you use formal terms. People will understand you but if you don't want to stand out in Puerto Rico, use "violeta".