The United States Congress is the legislative branch of the federal government and consists of two houses: the lower house known as the House of Representatives and the upper house known as the Senate. The words "Congress" and "House" are sometimes colloquially used to refer to the House of Representatives.
Republicans currently control the Senate (54 to 44 Democrats) and the House (246 to 188).
House of Representatives
The United States House of Representatives is one of the two houses of the United States Congress. It is frequently referred to as the House.
The United States Senate is the upper house of the bicameral legislature of the United States Congress.
Lower house. Responds to the needs of the people faster since representatives only have a two year term. Laws dealing with revenue must start in the House.
Upper house. The six year term means the Senate can be slower and consider the long-term effects of laws.
2 years. All 435 seats are up for reelection every two years.
6 years. Here there is a continuous body idea. Only 1/3 of the senate seats are elected every two years. So only 34 or 33 senators are up for election at one time.
Based on the population of each state
Two for each state
Based on Virginia Plan
Based on New Jersey Plan
Elected by the House of Representatives. The current Speaker of the House is John Boehner (R).
Vice President Joe Biden is President of the Senate. He only votes in case of a tie. When the Vice President is not available, the President Pro-tempore, a senator elected by the Senate (currently Republican Orrin Hatch), takes over.
editSeats in the Senate vs House of Representatives
While there are 100 seats in the Senate (two from each state), there are 435 seats in the House of Representatives, one each from the various congressional districts (the number of congressional districts in each state is determined based on the population).
A line graph showing which political parties have controlled the U.S. House of Representatives and Senate over the years. Click to enlarge.
The rule that each state should have equal representation in the Senate (two senators) irrespective of how small or populous the state is, is not universally popular. This article in The New Yorker dissects it well:
James Madison and Alexander Hamilton absolutely hated the idea that each state should be entitled to the same number of senators regardless of size. Hamilton was withering on the topic. “As states are a collection of individual men,” he harangued his fellow-delegates at the Constitutional Convention in Philadelphia, “which ought we to respect most, the rights of the people composing them, or of the artificial beings resulting from the composition? Nothing could be more preposterous or absurd than to sacrifice the former to the latter.”
The video below describes the differences between the House and Senate, what the requirements are to be eligible for a seat in the House or Senate, and what rights representatives and senators have as elected officials.