Since the United States national legislature is bicameral, there are three different titles for legislators: Representative (Member of the House of Representatives), Senator (Member of the United States Senate), and finally Congressman/Congresswoman (An individual member of the House of Representatives, synonymous with “Representative”).

It is important to note that although it is technically a term for members of either house, “Congressman/woman” is used almost exclusively to refer to members of the lower house in the United States in formal address. Indeed, it would likely be considered a faux pas to refer to a member of the United States Senate as “Congressman/Congresswoman”.

If you visit this site it explains what the House and the Senate Do and why they are Different.

http://www.purepolitics.com/edu/mrsmith/housevsen.htm

A Senator is a member of the US Senate.

A Representative is a member of the House of Representatives

A Congressman is someone who is EITHER a US Senator or a Member (Representative) of the House of Representatives.

A Representative serves in the House of Representatives

A Congressman serves in Congress.

Congress = House of Representatives + Senate

Senators are elected by the people and their are two in each state. There are 100 senators. Before the 17th ammendment to the constitution, Senators were elected by state legislatures. The Senators serve six year terms and have the right to approve presidential appointments such as supreme court justices and sign foreign treaties with other countries. Senators are also jury members should any member of government be impeached.

Representitives serve in the House of Representitives. They serve only two year terms. There are 423 Representives and each state is awarded a certain number based on the population of the state. Representives have the right to bring charges against (impeach) the president or another member of government. Also, any bills having to do with revenue (money) come from the house of representitives.

Senators are required to be 30 years old, are elected to 6 year terms and are elected in cycles so that only 1/3 of the Senate is up for election in any given election year.