dinner 和supper在英文中好像都是指晚餐，那么两者有什么区别呢？

dinner：一词常用来表示一天中的正餐（main meal）它一般是指晚餐，而不指午餐，dinner一词比较正式，邀请朋友赴晚宴常用。国内很多认为dinner也可以指午餐其实是不准确的。dinner指午餐supper指晚餐已经是过时的用法。

supper：所指的晚餐不是正餐，指的临睡前吃的夜宵，即睡前的少量进食。此外，在苏格兰地区，supper可用来指普通百姓比较简单、比较晚的一餐。supper还固定用来指圣经中耶稣受难前的最后一次晚餐——lord's supper或last supper.

dinner和supper在美国的用法：

“Supper” and “dinner” mean the same thing: the last meal of the day that is served in the evening.
In most parts of the U.S., especially in urban (city) areas, you’ll hear “dinner” more often than “supper.” “Supper” is also a bit old-fashioned in most parts of the country.  You may hear it used for talking about eating that meal at home; it’s less common to hear someone say that they are having supper at a restaurant.
In some rural (countryside) and Southern parts of the U.S., you may hear “dinner” used instead of “lunch” to mean the meal in the middle of the day, and “supper” used instead of “dinner” to mean the last meal of the day. However, this usage is also becoming less common these days and the terms “breakfast,” “lunch,” and “dinner” are the most common to describe the three meals Americans typically eat each day.
For most Americans, mealtimes are as follows: Breakfast - 6:00 to 9:00 a.m.; Lunch - 11:00 a.m. to 1:00 p.m.; and Dinner/Supper - 6:00 to 8:00 p.m. Of course there are many exceptions (things that do not follow the rules) depending on people’s schedules and preferences, but these are times that you can expect a restaurant to serve these types of meals.
Many restaurants in Los Angeles, as in many cities, close at 9:00 p.m on weekdays (Monday through Friday) and at 10:00 p.m. on weekends (Saturday and Sunday). You will still be served if you arrive anytime before closing time, but late-comers will be turned away (not allowed to enter). There are, of course, restaurants that cater to (are made for; are specifically for) late-night diners (eaters), and many of these are open 24 hours.

而在英国，这种用法也受到美国用法的影响：

When I was a child, growing up in the suburbs of London, it was breakfast - dinner - supper. That seems to have changed in the late 70's and since then I and all my family have eaten breakfast - lunch - dinner. I suspect this is an Americanism which crept in in the 70's. It would seem strange to me now to describe the evening meal as "supper"!

而且dinner和supper有食量上和时间上的差别：

To my knowledge 'supper' is the light meal which we take before going to sleep, usually night times and 'dinner' is that meal which would be heavy in a day(which some one throws for us as a party), can be lunch.