They refer to the same meal, but 'supper' is more formal than 'dinner'.

It depends which English speaking country you come from. In Australia we say dinner or tea. We don't use the word supper.

no need for the word supper in your language learning in my opinion

When I was a little girl I would spend my summers on my grandparent's farm in Arkansas. Each day we would eat breakfast, lunch, dinner, and then supper. "supper - Any light evening meal, especially one taken late in the evening: an after-the-theater supper." Supper was usually a tomato sandwich and some blackberries or something similar. I don't know if this is a southern expression or use of the word. For most Americans supper and dinner mean the same thing. However, Americans rarely use the word, "supper."