The Senate is known as “The Upper House” and was originally conceived by the framers to be more aristocratic. In the original constitution senators were indirectly appointed by the state legislature but this was changed by the 17th amendment and they are now directly appointed by the people.
The Senate has two senators per state (100 senators) as it was intended to be the Federal house. It has 6 year terms which allows for senators to worry less about their popularity and it is chaired by the Vice President who may serve as a tie-breaker but it is not a voting member. Once the house has drawn up articles of impeachment the trial will occur within the Senate.
The Senate has the unique privilege of unlimited debate which allows for the Filibuster. All nominations will go through the Senate (Judicial, Cabinet, Ambassadors). By a 2/3 the Senate may also ratify or reject treaties negotiated by the President.
The House is known as “The Lower House” and as the National house it was always intended to be the democratic with proportional representation. Each member serves a 2 year term and thus is more accountable to the people.
There are 435 members and it is chaired by the Speaker of the House who is typically a member although that is not a requirement. Debate is limited with members being given a portion of time on the floor. It is in this house that articles of impeachment are drawn up. All revenue bills must originate in the house where the members are closer to, and therefore theoretically better understand, the people.