Comparative Reading Comprehension passages are the baby of the LSAT, having been added to the test in 2007 (practically a blink of an eye for an organization that takes a month to score a Scantron). As the name would suggest, the questions focus on comparing the two passages: Which of these is supported by one passage but not the other? Which is something that both authors have in common? And so on.
Sufficient and necessary assumption questions are asking about two very different types of assumptions, but both question types have something in common: The conclusion almost always introduces new information, and finding the correct answer requires identifying and handling that new information appropriately. Sufficient Assumptions Almost all sufficient assumption questions have new information in the conclusion