The Stamp Act Congress was a meeting of delegates from nine of the American colonies that was convened in October of 1765. The meeting was held in New York City. The purpose of the congress was to try to formulate a response to the Stamp Tax that the British had recently imposed on the colonies. The colonies were very much opposed to the tax and some in the colonies wanted to present a united front against the tax so as to be able to get the Parliament to reconsider.
The Stamp Act Congress put out a "Declaration of Rights and Grievances" and sent it to England. Parliament did not consider it, but it did repeal the Stamp Tax in response to various protests in both the colonies and in England.
The Stamp Act was when colonists didn't want to be taxed by the British for their stamps. The Stamp Act was passed by Congress in 1765.