This system of legislature division is known as a Bicameral system or Bicameralism and is contrasted by a unicameral system, which only has one house in a Legislature. In Bicameralism, the legislature has two separate bodies that both must pass a bill if it is to become law. Generally, there is a "Lower House" that have a larger number of seats for members and a shorter term, and an "Upper House" that has a smaller number of Seats and longer terms. This system dates back to 14th century England, which created the two houses to represent to different and general interests. Getting the first out of the way, the "Lower House" or "Commons" represented the Commoners, which always has more members than those represented by the Upper House, hence the size. They also serve shorter terms compared to the Upper House, because the will of the people is frequently changed and often fickle.
The Upper Houses are typically difficult to characterize, but suffice to say, they typically do not represent the common man. When first used by the British, the Upper House was made up by those who had peerage titles (Knights, Barons, Counts, Dukes) which were collectively known as "Lords" hence the UK's name of their Upper House as "The House of Lords". As bicameralism moved to other legislatures, however, many were adopted by nations which had no peerage system OR more likely abolished it, had other methods for naming members to their Upper House. While not always true, (and most relevant to India specifically) came from the Establishment of U.S. Congress... the net effect is that almost all Upper Houses are more permanent and thus act as a check on popular whims by considering the long term impact of legislation of legislation as well as having the experience to know when bills should be killed because they tried it before, it didn't work.
The U.S., following Independence was very markedly against all things Monarchy for propaganda purposes, but in truth many of the changes the U.S. made to their government structure were improvements on the balance of powers that lead to an out of control Legislature. The U.S.' Lower House (House of Representatives) would funciton almost identically to the House of Commons, but since Peerage wasn't popular in the U.S. they couldn't make Peers. At the same time, there was a huge fight among the drafters of the Constitution among the way represntation worked. Since the U.S. was a Federation and States were willingly giving up some but not all self government policy, a "Commons" would benefit the states with higher populations than those with smaller populations. The drafters from smaller states pointed out that this would mean that the House of Reps would run the risk of small states getting rotuinely out voted by large states because they didn't have an even consideration, which was was essentially the problem that led to the whole war for independence in the first place (Tyranny of Majority). Meanwhile the members of the big states argued that giving each state an even number of seats meant their people now had less voting power behind their and gave rise to a Tyranny of Minority (which is traditional tyranny anyway.). Thus came what's known as the Virginia Compromise, which held that the lower house was to represent the people and the Upper House would Represent the states (originally the governments of the states, as they were indirectly elected, but in the Modern U.S. they tend to represent the sates majority vote). Thus in the modern U.S. make up, California, the state with the largest population, is more powerful in the House, where it has 53 votes (Starting with the 2022 elections) compared to one vote afforded to Wyoming, the lowest populated state . Meanwhile, Wyoming is disproportionately more powerful in the Senate, as it's two votes represent far fewer people than California's two votes.
All of this is because in Federal Nations (Which include India and the U.S.) the national government is more concerned with matters that concern two or more states than matters concerning a more local state. As such, states and their people have different needs that means they won't always align. For example, in either the U.S. or India, a bill that will provide additional money to states to purchase new snow plows will get different support from (apologies, I do not know India states) Alaska (Himalayan State) which has frequent Snow than say Florida (Tropical State) which won't get to see much of that money BUT those same States might support funding for protecting endangered animals because both have very endangered animals native to their states(Alaska and the Polar Bear, Florida and the American Alligator. India would have the Snow Leopard in the Himalayas and the Indian Elephant in the tropics).
