1. Every state is represented by two Senators, but by different numbers of Representatives based on their population. The Senate gives small states equal representation, because the Senate is about representing the states. The House is about representing the people directly.
2. Senators serve for 6-year terms. Representatives serve for 2-year terms. That is supposed to ensure that the House responds more quickly to change and Senators can focus on legislation without having to split their effort between legislation and reelection as often.
3. Spending bills have to originate in the House. Anything government spends money on has to be the House's idea. Supposedly, the Senate is about loftier ideas than just money and budget.
4. The Senate approves some of the President's decisions, especially his appointments of high figures (federal judges, Cabinet members, agency heads, etc). The House has no say in that stuff.
5. While pay for Senators and Congressmen is generally the same, the Speaker of the House gets paid significantly more than the President pro tempre of the Senate.
