It’s a matter of usage. Dinner, by definition, is the chief meal of the day, eaten at the noon hour or in the evening. Supper is an evening meal, especially when dinner is taken at midday. In my part of the South we eat breakfast, dinner and supper because our main meal has traditionally been at noon. Even if we eat our main meal in the evening, we still refer to the noon meal as dinner and the evening meal as supper. In many other parts of the US, people eat breakfast, lunch and dinner because their noon meal is light and their main meal is in the evening. I think "supper" used to used more frequently but only certain areas seem to retain the use today. My non-southern girlfriend always confuses me when she refers to the evening meal as "dinner.".

The people above all come from America. In England we consider Supper to be a very light snack meal eaten late at night,usually before bed.Our meal order is as follows: Breakfast,lunch,dinner,supper A lot of people don't eat supper here. When I do,my supper is usually a bowl of cereal and I eat it at about 10pm. Also please not,in England,the midday meal is always called lunch,not dinner.

What the other commenters have said is true, but personally, I think it's safer to always use "dinner" for the evening meal. Most people should know what you mean, and "supper" usually comes across as a bit old-fashioned (I've never heard anyone under 30 use the word "supper," actually. Not that there's anything wrong with that, but still). Just my personal opinion, of course! ^_^

Dinner--->A banquet or formal meal in honor of a person or an event. Supper--->A light evening meal when dinner is taken at midday. *Dinner is considered to be the "main" or largest meal of the day. Whether it takes place at noon or in the evening is mostly a cultural thing. Supper is more specifically a lighter evening meal. Lunch is almost the midday equivalent of Supper — it's also a lighter and less formal meal than Dinner, but is used specifically when referring to a midday meal. http://english.stackexchange.com/questions/22446/lunch-vs-dinner-vs-supper-times-and-meanings