"Gemi"= Big. Long distance "Vapur"= Small. Short distance

People living in Istanbul uses "vapur" instead of "gemi" in bhosphorus

"Gemi" is more general than vapur. Actually gemi is the name for a "genre". Vapour is a more specific name. The word "vapour" passed from French to Turkish. It is originally a french word. But gemi is a Turkish word. there were so many subgenre under the the word "gemi". Çektirme, Kalyon, Kadırga are some old names for different "gemi"s. You can define vapur as "buharla çalışan veya kısa mesafelere yolcu taşıyan bir tür gemi" " a kind of ship ran by steem or carrying passengers for short distances".