以上两个词中文意思相近，有时多少可以互相替换使用，但一般情况下应该使用哪个词都已经预定俗成。
Dinner既可指午餐，也可指晚餐，但通常表示正餐。lunch只指午餐，通常很随意。
Dinner can refer to either the second or the third meal of the day.It is usuaIIv the main meal and can be either formal or informal.Lunch refers only to the second meal and is usually casual.