Confusing words "dinner" and "supper".

I have been learning English for a very long time by now and I have always wondered why Englishmen the English use both words, "dinner" and "supper" for their evening meal. And Finally after today listening to a podcast today, I've found out about the difference between them. So an The average Englishman has will have a breakfast in the morning, lunch in the afternoon and supper in the evening . ut When he or she dresses dressing up for a meal and has it with family or friends this evening meal is called "dinner". Now I m very interested about how the Americans use them do they use both words in the same way as British?

SUPPER:
1. A light evening meal when dinner is taken at midday.
2. A light meal eaten before going to bed.

DINNER:
1.the main meal of the day, eaten in the evening or at midday.
2.a formal meal in honor of some person or occasion.

Terms:
The word dinner comes from the french word diner, which means the chief meal of the day. Dinner can also mean a more sophisticated meal like a banquet. The word comes from the latin disiunare, which means to break fast (like in the english word breakfast).
In the United Kingdom and Ireland, supper was originally a light meal eaten just before bedtime. This meaning is still retained for the case of an "after-theatre supper"

In some countries, "supper" is equivalent to a midnight snack.  In the US, at least on the West Coast, we don't use "supper" at all.  The meanings are not only cultural but personal as well.

http://dictionary.reference.com/help/faq/language/d68.html