This is a difficult one, because even native speakers can't agree on the difference. Here are two things that we generally do agree on, though: Supper is an evening meal. Dinner is a main meal. This usually means that it is an evening meal, but it occasionally refers to a meal earlier in the day. In some areas of the British Isles, working class people call their midday meal 'dinner'. The main family meal at Christmas is called dinner, even though it is eaten during the day. Some people use these words interchangeably, but for most of us, dinner is a more formal or more substantial meal. Supper may be a lighter meal, perhaps simple like soup and a sandwich, often eaten later. For example, if you invite your friends round to your house for dinner, they would expect a carefully prepared meal of three courses, and you would expect to spend most of the evening sitting around the table enjoying this meal. But, if you are going out to a concert with your friends for the evening, you might invite them over for supper before or afterwards. This would be a much quicker and simpler meal. The way people use these words varies according to region, and even the age and class of the speakers. As I said, it's a difficult one!

quick response please