1. The world can simply be divided into richer and poorer countries. This division is made based on the economies and standard of living in the countries.
In general, the richer countries in the world are located in Western Europe, North America (USA and Canada), part of East Asia, and Australia. The reason why the richer countries are located at these places are because these countries were the ones that started off the Industrial Revolution, had colonies, lot of natural resources at disposal, which gave their economies a big advantage. Also, these countries have well developed market economies, highly educated populations, and their industries are diverse and well developed.
The poorer countries are mostly located in sub-Saharan Africa, part of Southeast Asia, South Asia, Central America. The reason why this regions have the poorest countries is that they started to industrialize very late. They had or still have dictators as their rulers. The economies are often based on one or few products, and the corruption is on a very high level.
2. The life expectancy around the world varies, in some cases greatly. It is something that is directly connected to the situation in which a country is, or rather the living the conditions of the people.
The countries that have high life expectancy are the ones that are well developed. The people in this countries have good living conditions, good health care, have the institutions at disposal, have rights, earn solid amounts of money. Such countries are Japan and Island.
The countries that have low life expectancy are the poor ones. The people in this countries live in terrible conditions. They don't have their rights guaranteed, they don't have, or if they have it is a very poor health care, the institutions are not available to them, they earn very little money, the water and food are scarce. Such countries are Burundi and Chad.