Something educative teaches you something. A trip, a film, a conversation, even a mistake can be educative if you come away knowing more, or seeing the world a little differently. It is a quieter, more formal cousin of educational. Though actually, educational is the everyday word, and it often just means 'to do with school' — educational policy, educational toys. Educative is less about the school system and more about the effect: this thing formed you; it taught you. You will meet it in thoughtful writing more than in chat. People do not usually call a person educative; they call an experience, a book, or a moment educative.