Cartogram of Population

Here is an ordinary map of the world:

and here is a cartogram representing world population:

From http://www-personal.umich.edu/~mejn/cartograms/

In this map the sizes of countries are proportional not to their actual landmass but instead to the number of people living there; a country with 20 million people, for instance, appears twice as large as a country with 10 million.

Which countries have the most people?

Which countries look very different on this map, compared to the ordinary one?

Why might a country that appears large on the ordinary map appear small on this cartogram?