Final answer:
The key difference in the original Constitution was that Senate members were selected by state legislatures, while House members were directly elected by the people. The Senate was more insulated from electoral politics, providing a check on the House's direct representation. This changed with the 17th Amendment's direct election of senators.
Step-by-step explanation:
In the original Constitution, Senate membership was determined very differently compared to the House of Representatives. While House members were directly elected by the people, representing small geographically defined districts within each state, the original Constitution provided that Senate members were chosen by state legislatures. This was a fundamental aspect of the framers' vision of a bicameral legislature, where the Senate acted as a check on the more frequently elected House, embodying a more deliberate and less populist governing body, somewhat insulated from the immediate pressures of electoral politics. Over time, however, this approach changed with the ratification of the 17th Amendment in 1913, which then mandated the direct election of senators by the people, aligning Senate elections more closely with the democratic process used for House representatives.