What is the difference between a senator and a representative?

Congress has two chambers. The House of Representatives has 435 voting members apportioned among the states by population, each representing a district of roughly 760,000 people and serving two-year terms, so the entire House faces election every even year. The Senate has 100 members, two from every state regardless of population, serving six-year terms staggered so about a third are elected every two years. That structure was the founding compromise between large states, which wanted representation by population, and small states, which wanted equal standing.

The chambers hold distinct powers. Revenue bills must originate in the House, and the House alone can impeach federal officials. The Senate alone confirms presidential nominations to the cabinet, ambassadorships, and federal courts, ratifies treaties by two-thirds vote, and tries impeachments. Both must pass identical legislation for it to reach the president. Procedurally the House operates by majority rule under tight time limits, while the Senate's tradition of extended debate gives its minority substantial power through the filibuster.

The population math produces the disparity people argue about. Wyoming's roughly 580,000 residents and California's roughly 39 million each have two senators, so a Wyoming voter has about 67 times the Senate representation of a Californian, and the Senate can be controlled by senators representing a minority of the national population. Representatives, by contrast, are the more directly accountable body, which is why the framers gave them the two-year term and the power over money. Delegates from the District of Columbia and the territories sit in the House but cannot vote on final passage.