Answer:
The House has a reputation of being much more contentious and impulsive when it comes to legislation. By comparison, it is fairly easy to be elected to the House, which means you have won a congressional district vote vs. a Senate seat which is a statewide vote. So Senators, by definition, usually have to be more moderate than Representatives in order to get elected.
The House will often vote for controversial policies such as abortion limits or banning flag burning, knowing full well they can make such votes without it having a chance to pass the Senate. So they can posture and throw red meat to the crowds in their districts without actually having to accomplish anything.
