This document discusses several factors that can influence differences in levels of development between countries: 1. Colonialism - Today's developing countries were often former colonies that were exploited for their raw materials, limiting their own development. Exceptions exist, like Singapore, which developed rapidly despite being a colony. 2. Natural resources and climate - Countries with valuable resources like oil can develop faster, but exceptions like Nigeria exist. Climate also influences development, though technology can overcome limitations. 3. Cumulative causation and core-periphery dynamics - As resources and people flow to core urban areas, they become richer while peripheral rural areas become poorer through "backwash effects," though governments can encourage "spread effects" to poorer regions