壱, 弐, 参 vs 一, 二, 三


Can you tell me the difference between 壱 and 一, 弐 and 二, 参 and 三?

Do these pairs have the same meaning? If yes, why do we use different Kanji?
If no, what is the difference in their meanings?

Can you give example usage in sentences for each of them?




The more complex ones are called daiji (`大字【だいじ】`). Find out more here.
<http://www.jekai.org/entries/aa/00/no/aa00no38.htm>




The "difficult" kanjis are used in legal documents, or for style (in some
commercials, e.g. when you have three days of sales).

I guess we don't use them because they're obviously harder, but I don't know
where the "simple" ones come from.

