Both words are used to refer to acts — religious or civil — by which a man and a woman become husband and wife. Of the two, “marriage” is more common. It can be used to refer to the actual ceremony that takes place or the spiritual union entered upon by the two individuals.
*The two have had a long and happy marriage. *I am sorry to say that I can’t be present at your marriage.
“Wedding” is used to refer to the ceremony and the festivities which follow it. Unlike “marriage”, it cannot be used to talk about the relationship between the married couple. A “wedding” may last only an hour, but you can remain married for 40 years.
*Vinita’s wedding is today. Unfortunately, I won’t be able to make it. *Please don’t invite too many people to the wedding.